The Complete Fog Light DIY
Created by Doohickie. Let him know if he spelled anything wrong
or if you have any suggestions for this DIY guide.
Special thanks to ElantraClub
members wills03 for getting the ball rolling by devising the mounting scheme for the fog
lights, and silet for coming up with the routing between the engine and passenger
compartments, and asking all the right questions at the right time to make sure I
thought this through. I also have to give credit to CardassianCruiser for inspiring the
rear fog light mod by his DIY for hooking those lights up as additional brake lights.
More than any other DIY I know of, this was truly a team effort.
Introduction
Front Fog Lights
.....Wiring Considerations
..........Quick & Dirty Wiring
..........Using a Relay
..........OEM Fog Light Wiring
..........Alternate Fog Light Wiring
.....Parts and Materials Needed
.....Mounting the Fog Lights
.....Engine Compartment Wiring
.....Wire Routing- Engine Compartment to Passenger Compartment
.....Fog Light Switch
.....Passenger Compartment Wiring
Hooking Up Rear Fog Lights (XD and XD2 Hatch Only)
.....Rear Fog Lights as Brake Lights
.....Rear Fog Lights as Fog Lights
..........Hatch and Door Sill Wiring
..........Passenger Compartment Wiring
Introduction
There's something for every XD Elantra owner in this DIY.... except for owners of sedans
with factory fog lights. For everyone else, check it out:
Installing Front Fog Lights (XD2 shown, other models possible)
Wiring Rear Fog Lights to Brake Circuit (Hatch only)
Wiring Rear Fog Lights as, well, Rear Fog Lights (Hatch only)
If your Elantra did not come with factory fogs, most of the fog light wiring was not put
into the car. That leaves several options: 1) Wire up fog lights quick and dirty using
wiring that comes with the kit; 2) Wire the fog lights up using provisions for the fog
light wiring that already exist in the car; or 3) Duplicate the OEM wiring schematic
without opening up the fuse box.
Front Fog Lights
Wiring Considerations
Before going into what is needed and how to install the fog lights, a discussion of
wiring options will help you decide how to connect your fog lights. In the most basic
wiring, the fog lights are controlled by a simple circuit. However, this circuit
will not automatically turn off when the car is shut off. The other extreme is to
hook up the fog lights exactly the same as they would be in an OEM fog light installation,
including an OEM multifunction switch that controls fog lights from the headlight stalk.
This option means that your fog lights only go on when the headlights are on. A middle
ground is to do a custom installation using some features of the OEM wiring, but hooking
things up so that whenever the marker lights are on, the fogs can be turned on. The
benefit of this version is that the fog lights shut off automatically when you leave the
car, but can come on almost any other time, as long as your marker lights are on.
Quick & Dirty Wiring
If you choose this option, the fog light kit you buy should include the basic
wiring diagram you will need. You can use the DIY instructions for
mounting the fog lights, running
the wires between the engine and passenger compartments, and mounting
the switch, though.
Using a Relay
A relay is an electrical device that does pretty much what the name implies:
It takes a switch signal and relays it (passes it on) to another circuit. When electric
current is applied to the coil contacts, it uses electromagnetic force to close a switch
between the high-current contacts. When the current is removed, a spring moves the switch
open again. The point of using a relay is that the wires that run to the switch draw
very little current- just enough to operate the relay coil (which isn't much).
The fog lights, on the other hand, draw several amps which is a relatively high current.
By using a relay the wires carrying the high current to the fog lights don't have to go
into the passenger compartment, and if any other circuits are involved with deciding
whether to turn on the fog lights, they don't have to be high-current circuits.
How Stuff Works has a pretty
good discussion of relays if you are unfamiliar with them.
A basic relay circuit looks like this:
OEM Fog Light Wiring
Going from that basic circuit, let's look at the fog light wiring on the XD2 Elantra:
Pretty much the same, right? If you look at the high current side of the circuit on the
right side of the diagram, Pins 1 and 2 on the relay, you see that it is largely the same as
the simpler diagram above. The only significant differences are that there is a fuse between
the battery and the relay (always a good practice), and there is a third light that
comes on when the fogs are turned on; this is the indicator light on the instrument
cluster. That part, at least, is pretty straightforward, right?
Now let's take a look at the other side of the relay, the part that determines when the fog
lights come on. There are some twists and turns, but basically it's saying that power can
only be applied to the coil under certain conditions:
The current for the coil is turned on whenever 12 volts from the battery gets to one
end of the coil and the other end is connected to ground, completing the circuit.
This happens when ALL of these are true (follow the green line starting from "HOT AT ALL
TIMES"):
1. The Tail Lamp Relay is turned On. This is on whenever the marker lights are on, in
Parking, Low Beam or High Beam positions of the headlight switch. (Note that the ETACS
can turn off the Tail Lamp Relay by interrupting its coil's path to ground through the
"Tail lamp relay auto cut control" circuit. Because of this when the Tail Lamp Relay
is turned off, the Fog Lights are also turned off. This is the feature that turns
your fog lights off automatically when the car is shut off and the door is opened.)
2. The Front Fog Lamp switch is turned On.
3. The Flash-to-Pass/Low Beam/High Beam switch is set to Low Beam.
4. The Headlight Switch is in the Head position.
5. There is also a connection from the ETACS labeled Fog Lamp Relay that, I believe,
simply tells the ETACS that the Fog Lights are turned On. I don't think it affects
the state of the lights, though; it just senses it.
In all of that wiring, three wires actually go between the passenger compartment and the
engine compartment. These wires are not included in the car's wiring if the Fog Lights
were not put on the car when it was built. To get true "OEM" behavior of the fog lights,
these wires need to be run between the engine compartment and the passenger compartment.
The connector pins for these three wires are highlighted in the schematic in purple, and
the wires that need to be run are in red. (The wire shown in dashed red to the ETACS does
not need to be run for the fog lights to function.)
The three wires are:
Connector EM02, Pin 2: Provides power from the marker light circuit to the Fog Lamp Relay.
Connector EM02, Pin 3: Provides the connection from the Fog Lamp Relay to the Fog Lamp
Switch on the multifunction switch on the steering column (and eventually to ground).
Connector EM02, Pin 4: Provides a connection to the indicator light in the instrument
cluster (which already has its own ground).
The good news is that Connector EM02 is easily accessible under the instrument panel
(more on that later). The other bit of good news is that once
the wires to the engine compartment are installed, you're done with EM02 because the
passenger compartment side of all these wires already go from Connector EM02 to the
passenger compartment fuse box, instrument cluster and multifunction switch.
If you're going to use an OEM multifunction switch that has a Fog Lamp Switch built into
it, the wiring you install will recreate the schematic above for the most part. You can
use the DIY instructions for mounting the fog lights and
running the wires between the engine and passenger compartments.
In this case, you will need to run three wires between the engine compartment and the
passenger compartment- EM02 Pins 2, 3 & 4.
Alternate Fog Light Wiring
If you are using an aftermarket switch, there is a slight change that can reduce the
number of wires needed between the engine compartment and passenger compartment from
3 to 1. The schematic ends up looking like this.
Note: There is an important difference between the schematic shown for front fogs
only, as opposed to front and rear fogs. The rear fogs cannot be powered off Connector EM02,
Pin 2, because the current draw of the bulbs may cause failure of the Diode Z02. Instructions
for tapping into another power source is included in the rear fog light section.
This looks a little different from the Hyundai schematic. The high current side of the
Fog Lamp Relay is the same; fused power goes to the relay, and then to the Fog Lights. The
real difference is in the circuit that turns on the Fog Lights; it is simplified. The marker
light power coming out of Connector EM02, Pin 2, goes to the aftermarket Fog Light Switch and
gets switched right away, and this switched signal goes to the indicator light on Connector
EM02, Pin 4, and also to the engine compartment to drive the Fog Lamp Relay. The Relay is
then grounded right there in the engine compartment instead of coming back to the multifunction
switch to be grounded. So out of those earlier conditions, the only ones that needs to be
met is that the Tail Lamp Relay and the Fog Light Switch need to be On. All the headlight
logic is removed. The one disadvantage is that since the indicator is driven directly
from the switch, it will go on even if the Fog Lamp fuse in the engine compartment is
burned out.
So the first step, then, is to decide whether to do the quick and dirty wiring, imitate
the OEM Fog Lamp wiring or use an aftermarket switch, and then to follow the appropriate
schematic.
Parts and Materials Needed
- A set of aftermarket fog lights. For XD2s (2004-06), 2-inch projector fog lights
are the best option ($20-50)
(Note: I bought mine at AutoZone for about $40, Blazer UltraWhite Series UW3675.
A similar fog light is sold (as of the writing of this DIY) at
Harbor
Freight for about the same price. As stated earlier, if no relay is to be used,
the kit includes everything needed to electrically connect the fog lights, including
wiring instructions and the switch. Even though I used a relay, I still used much
of the wiring supplied with the kit.)
- A relay, fuse connnector, and fuse block wiring to connect the fuse to the relay
and the relay to other components (from a junk yard, $5)
- A switch ($4)
(Note: If you use an OEM multifunction switch, this will be significantly more.)
(Note: I used a rocker switch that snapped into a 1/2" wide x 3/4" high hole. The
3/4" height snaps into the opening for the blank next to the XD2 panel lights dimmer.)
- 1/8" x 3/4" x 36" aluminum to make brackets to hold the fog lights (From Home
Depot, about $4)
- Extra hookup wire and electrical connectors, as needed ($5-10)
(Note: 18 gage wire is more than enough to carry the current required by fog lights,
according to Hyundai WebTech and the aftermarket fog light kit I bought.)
- Plastic conduit (about 10 feet) and electrical tape
Mounting the Fog Lights
The XD2, as mentioned earlier, has fittings in the bumper fascia intended for 2-inch
projector fog lamps. There are several sources for these such as auto parts stores.
Make sure you get what you want (whether fog lights or driving lights). If you have
an earlier model XD (2001-03), the openings in the bumper fascia vary. In general,
larger fog lamps fit in XDs than in XD2s.
On a hatchback XD2, the fog lights can be mounted without removing the bumper
fascia, although the reaches are tight. The fog light area can be accessed both from
below the bumper and through the holes in the front of the bumper fascia, which permits
the use of two hands and allows you to see what you're working on.
However, on a sedan, there are no openings around the fog lights (instead, there are
just black plastic closeouts). Because the only access is from the bottom, only one hand will
fit in at a time which makes the installation very difficult, if not impossible.
Removing the entire bumper fascia is recommended. Directions
for removing the bumper fascia are here.
If you have not already done so, take out the fog light blanks (the "fake fog lights" that
fill the holes) that are in the bumper fascia. There are two 8 mm hex nuts, one on
each side of each blank. The studs in the bumper that these nuts screw onto will
be used for mounting the fog lights. Here is a view of wills03's bumper fascia from
the inside, showing the fog light mounting studs (fog light blank has already been removed):
On the housing for the UW3675 fog lights, there is a mounting hole on either side.
Two L-shaped brackets for each light need to be fabricated to mount them to the fog light
attach studs. A template is provided to make the brackets if the UW3675 fog lights
are used. Otherwise, the fog light blanks can serve as a pattern for the brackets to
ensure a decent fit.
Each fog light requires two L-brackets: A longer bracket used toward the middle of the car,
and a shorter one toward the outside.
For the shorter brackets, I started with a 3-1/8" long piece of 1/8" x 3/4" aluminum
stock. I scribed a line 1-3/4" from one end and put it into a vice with the jaws right
on the scribed line (and the 1-3/4" length hanging down from there). I then took a
hammer and bent the aluminum over to about a 90 degree angle to make one of the outer
brackets.
I then did the same thing for the inner brackets, but this time I started with a 5" piece
and bent it over at 4". In this case I bent it to form an angle of a little greater than 90
degrees (about 100 degrees), and put a second bend in the 4" section, about 2-1/2" from the
first bend. After the bend, there should be a 90 degree angle between the two ends (see the
template).
Then I drilled 1/4" holes at the locations shown on the template. I made the holes slotted along
the axis of the bracket by drilling the hole through, then tipping the drill in each
direction along the bracket axis to form a slotted hole. This provides some adjustment
for mounting your lights. I then made one more bracket of each type for the other side.
Here's the sequence I used in drilling the holes:
Drill straight through:
Tip the drill one way:
Then the other:
Producing a crude-looking, but effective, slotted hole:
I used some slightly longer screws than the ones included with the fog lights so that they would
be long enough to go through the bracket, the housing, and into the threaded bracket. I
got them at junk yard; they are common screws used for things like attaching hood latches and
come loose with a 10 mm wrench and have a 6 mm thread with a 1 mm pitch. They are also
available at hardware stores. (The screws included with the fog lights might work but
might not fully engage the threads on the bracket.)
I attached the brackets to the fog lights, tightening the screws only hand-tight. Make sure
the fog lights will be right side up when mounted in the car (they are marked). I then
moved them into position, with the holes in the brackets over the studs in the bumper fascia,
and screwed the 8 mm hex nuts onto the studs, hand tight. Then I positioned the fog light
so it was in the middle of the hole and right against the opening, and tightened the bolts
attaching the brackets to the fog lights, and the nuts attaching the brackets to the fascia.
Of course, if you remove the bumper fascia, actually mounting the fog lights is ridiculously
easy, since you have ready access to the back side of the fascia. Note that where I used the
threaded mounting bracket, wills03 actually used separate nuts.
Once the fog lights are in place, run the wires for them. Starting from the right hand side,
hook all the wires together. At this point, you may want to temporarily hook the
supply wires to the battery and ground the black wires to make sure your fog lights work.
Disconnect the wires from power for now and insert the supply wire and ground wire for the right
hand fog light into a section of plastic conduit. If you had to remove the bumper fascia
to mount the lights, you may want to feed the wires through the bumper before putting the fascia
back on (although it should be possible to do so with the bumper fascia in place). The conduit
should be long enough to go from one fog light to the other, through the bumper.
Starting from the right hand side, feed the conduit with the wires into the end of the
bumper and push it through the bumper C-channel section to the other side of the car.
If the bumper fascia is off the car, this should be very easy. If not, it might be helpful
to remove the radiator guard and grill as shown in the
directions for removing the bumper fascia
to provide better access to the area between the bumper and the radiator.
I found the wires supplied with the kit were just barely long enough to reach between the
fog lights when going through the bumper. In fact, this phase of the project is probably the
most frustrating because it involves a lot of fishing wires through the bumper, and once they
are fished through, it wasn't that easy to connect them to the left hand fog light.
I brought the ground wires for the fog lights into the bumper area and grounded them on a bolt
I found that attaches a plastic guard to the body on either side of the radiator.
Once the fog lights are wired together and the grounds connected, connect the feeder wire
and run it up through the left fender area into the battery area. With the bumper in place, I
just pushed the wire up as far as I could from below, then fished it out from the top. I brought the wire to
near the fuse box and cut the excess off there, and crimped a male spade connector on the end.
Then I covered the wire with plastic conduit back to the bumper area, and used electrical
tape to attach it to the conduit that runs through the bumper, making a "T" connection where
the feeder wire goes in.
Engine Compartment Wiring
At this point, a decision needs to be made as to whether to duplicate the OEM fog light
wiring in the fuse box, or provide similar functionality outside the fuse box. I went for
the OEM-style.
If the fuse box connections will not be used, connect the inline fuse provided with the fog
light kit to the positive battery terminal. Run the output of the fuse to one of the high
current connections (typically labeled Pin 30) of a relay. Connect the other high current
connection (typically Pin 87) to the fog light supply wire. Connect one of the coil wires
(Pin 85) to the switch (coming from the passenger compartment), and the other (Pin 86)
to ground. The relay should be mounted securely; the forward mounting bolt of the fuse
box is a good spot.
To use the provisions in the engine compartment fuse box for the fog lights, first remove
the air box to give easier access to the fuse box. Remove the heat shield, which is
held in with four fasteners:
Next, open the air box and remove the air filter. In the bottom of the air box are three
10 mm hex head bolts:
Once the bolts are out, lift the bottom of the air box out of the car. It will be joined
to the resonator duct near the fender but should just slide up and out.
The next operation is to actually remove the fuse box. Before doing this, disconnect the
negative terminal of the battery to make sure nothing can get shorted or damaged while
working in the fuse box area. Then remove the bolts holding in the fuse box at opposite
corners:
Next move the fuse box toward the middle of the car to slide the pin on the fuse box out
of the fender. Once the fuse box is free, remove the bottom. Use a screwdriver to pry
the clips that hold the bottom onto the box. There are clips all around the perimeter of
the fuse box.
If you have fuse box wiring from another Hyundai that has the identical connectors, they
can simply be pushed into place from underneath the fuse box. I will admit that my wiring
was not identical. The Hyundai I found in a junk yard was similar, but it used the older,
larger fuses. The relays were the same, but the fuse connectors were different. I adjusted
by finding a connector pin similar to the one in my Elantra that fit into the fuse box,
but it fit best when inserted from the top. It had a length of wire on it, so I pulled the
wire through to the bottom and seated the pin, which fit the hole well. On the other end of
the wire, I crimped a standard female spade connector which happens to be the perfect size
for the larger high current terminals on the relay. I then snapped that spade into place,
as well as the other three which I got from the junk yard. At the end of each wire I crimped
a spade connector on to connect them to the rest of the fog light wiring.
I connected the wires as following (following the Alternate
Fog Light Wiring schematic above):
(The colors are listed so you can follow the wiring more easily the pictures; the colors
of the wires you install may be different.)
Relay Pin 1: Red with Blue Stripe; comes from Fog Light Fuse.
Relay Pin 2: Blue; goes to female spade connector (provides switched fog light power supply).
Relay Pin 3: White; goes to male spade connector (connects to switch in passenger compartment).
Relay Pin 5: Blue with Red Stripe; goes to ground lug (grounds the relay coil).
To fully duplicating the OEM Fog Light Wiring,
using a multifunction switch, the relay pins should be connected as follows:
Relay Pin 1: Comes from Fog Light Fuse.
Relay Pin 2: Goes to two female spade connectors (provides switched fog light power
supply AND goes to indicator light on Connector EM02, Pin 4 in passenger compartment).
Relay Pin 3: Goes to male spade connector (connects to Connector EM02, Pin 3 in
passenger compartment which goes to multifunction switch).
Relay Pin 5: Goes to female spade connector (connects to Connector EM02, Pin 2 in
passenger compartment which is grounded when low beam lights are on).
Here are a few views. From the top, the fuse map in the cover was used to determine which
fuse and relay locations would be used for the fog lights. See close-up view for details.
The connections are made from the bottom: Red with Blue Stripe goes from the fuse block to
Relay Pin 1, and Relay Pins 2, 3 & 5 are brought out of the fuse box (on the side near
the fender) to connect with the rest of the fog light wiring.
Once the wires are in, bring the wires from Relay Pins 2, 3 & 5 out through the side
of the relay box near the fender, and snap the bottom cover back on the fuse box. If using
the Alternate Fog Light Wiring schematic, the ground
wire coming from Relay Pin 5 should be long enough for the ground lug to reach the forward
attachment bolt of the fuse box; this bolt goes directly to body ground. Don't put the
fuse box in place until all the wiring is checked, but go ahead and bolt the ground lug to
fender using the fuse box bolt; hand tight is good enough for now. (If using the
OEM Fog Light Wiring schematic, make a temporay connection of
the female connector to ground.)
Now plug in the relay and reconnect the battery. The relay connections can be tested by
connecting a circuit tester or voltmeter to the fuse connector that is wired to Pin 1 and
also the wire connected to Pin 2, then connecting Pin 3 to the positive battery terminal
(with Pin 5 already connected to ground). You should hear the relay click when the final
connection is made and there should be continuity between Pins 1 and 2.
If the relay circuit works, disconnect Pin 3. Now test it with the fog lights. Connect the
fog light power connector (male spade) that was brought up to the fuse box area
to the female spade connector connected to Pin 2 of the relay. Put a 15 amp fuse (or
whatever the fog light kit requires) fuse into the fog light fuse position, and reconnect
Pin 3 to battery positive. This should energize the relay and turn on the fog lights.
Disconnect the wire that goes to Pin 3, the battery, and remove the fuse for now.
If you are completing the job at this time, do not bolt the fuse box back in just yet;
however, this is a pretty good point to take a break. If you are not completing the whole
job now, bolt the fuse box back in place. Make sure there is NO fuse in the fog light
fuse conector, but make sure all your other fuses are in place (the four closest to the
fender and the two furthest away). Reconnect the battery and reinstall the air box. The car
should now start.
Wire Routing- Engine Compartment to Passenger Compartment
The wiring between the passenger and engine compartments will run through the fender.
To access the area, remove all the plastic fasteners and screws in the plastic fender
liner, and remove it. It is possible to do this without removing wheel, but access is easier
with the wheel off the car. From the inside of the car, remove the plastic trim piece on
the inside wall just forward of the driver’s door sill. It is held in with one screw and
one pop fastener.
Once the fender liner is out, a large harness should be visible. It enters a grommet
at goes into passenger compartment toward the rear of the fender. In the picture, the
harness is on the right and the hood release cable is on the left. (If running a single
wire, the hood release cable grommet is also a possibility, but this area is not as well
protected by the fender liner as the harness.) Only half the harness grommet is visible
from outside. There are actually two boots, one inside, one outside, molded into one piece.
Pull the grommet out of the body and punch a hole in the outside end with an awl
(be careful using a sharp instrument around the wiring). Tape the three wires (with
different insulation colors) to be passed through to a coat hanger or one conductor of
insulated household wiring, and push it through the hole in the grommet and out the
slit on the passenger compartment side. Use a generous length of wire both inside
and outside the car (it can be cut to length later). Tape the area where the grommet
was punctured with electrical tape. To protect your wires, cover the the three added
wires with plastic conduit.
Run the wires to the front of the fender area. At the forward end, follow the wire
harness into engine compartment. Leaving several inches of extra wire at both ends,
strip and crimp on the spade connectors to hook the wires up per the schematic you are
using. Check continuity at between the engine compartment and the passenger compartment.
Reinstall the fender liner. Here is a picture I took at a junkyard that shows the body
features inside the fender area.
Fog Light Switch
If you don't have the multifunction switch with the fog light switch built in, you need to
figure out what kind of switch to use and where to mount it. There are several options. On
2004-2006 model year Elantras, there is a switch blank next to the headlight dimmer that is
easily removed. The switch can be mounted in that blank, or a piece can be made to replace
the blank if you want to be able to revert back to stock in the future. I used two switches
since I also wired up the rear fog lights as well, but if you're just doing front fogs, the
easiest way to mount the switch in this area is to get a toggle or rocker switch that mounts
into a round hole, and simply drill a hole in the switch blank (or the piece you're using
in its place). I'll show how I made my switch plate for two switches, but you can use a single
switch if you're just doing front fogs.
If you don't want to modify your dash, you can mount the switch in a less obvious spot, such
as under the dash, in the glove box, or in the console. If you're going to wire it up to
the indicator in the instrument panel through connector EM02, hiding the switch is fine
because you'll still know when your fog lights are on even if you can't see the switch.
Because I chose to mount the switch in the dash fascia, I decided to wire up the switch to a
connector behind the dash fascia and can be easily disconnected if I want to
take my dash fascia off for other mods. For a connector, I went to a junkyard and got a 4-pin
connector out of the door of an old Honda Accord. The non-weatherproofed connectors in the
Accord door are similar in style to the Elantra, have a positive connection, and a tab to
push to release it.
Removing the switch blank next to the headlight dimmer is easy. Remove the coin bin between
the steering wheel and the driver's door, and reach up to the back side of the connector.
There are catch tabs on either side of the blank. Squeeze these tabs and the blank should
pop out.
The following pictures show the switches wired to the connector. First, I cut the wires
coming out of the connector down to about a 4 inch length, keeping the extra for some wires
that, in my case, run between the switches, then I crimped on female spade connectors that
will plug into the male spades on the back of the switch. If you are using just a single
switch, you will only need two wires, three if the switch is lit to provide a ground for the
switch light. The 12 volt power from the marker light circuit goes to the PWR terminal on
the switch, the ACC terminal goes to the fog light relay, and the GND goes to body ground.
(If you look ahead in the next section, I drew a diagram of the connections for a front
fog light installation; there is another diagram in the front and rear fog light install
section.)
I taped up the spade connectors to keep them from shorting out on each other (as I
do with all my connectors) and plugged in the switches, checking to make sure
they worked as intended.
My original intent was to cut a hole in the original switch blank to snap the switches into,
but I ended up just making a new piece and pushing it into the hole in the dash fascia.
I traced the switch blank on a piece of plastic about 1/8" thick and cut it out with a
Dremel tool. Then I used the Dremel to cut a hole in the plastic piece sized so that the switches snapped in.
Finally, I took a piece of gray fabric out of my wife's quilt stash and covered the plastic
part before snapping the switches in for good, to give it a finished look. I then pushed
the whole thing into the hole in the dash fascia; it fit snugly. Again, if you're using
a single switch, one that goes into a round hole would fit would be easier to mount in the
switch plate, since it only requires drilling a hole.
The finished switch plate looks like this. I got a little fancy and made masks with the
foglight symbol on them, pried off the colored rocker piece, put the mask in and snapped
the switch back together.
Once all the wires were connected according to the schematic, the switch operated the
fog lights as well as the indicator light on the instrument cluster. (The indicator is
the green icon near the 40 mph mark on the speedometer.)
Passenger Compartment Wiring
This is probably the hardest part of the DIY in that everyone will do it a little
differently, depending on whether an OEM or aftermarket switch is used. This wiring
ties everything together, including the wires coming from the engine compartment, the
switch, the indicator, the power for the switch circuit, etc. To tap into a connector on
the car, I used pins scavenged from junkyard cars, and just pressed them into the connector.
The connector pin had a length of wire on it on which I crimped a spade connector that I
connected to the other wires as required.
If you look at the schematic I used, you will notice that I used male spade connectors
(as indicated by arrow heads in the schematic) on all wires that are grounded or carry no
voltage when they are not conneceted, and female spades (shown as arrow tails on the
schematic) on all the wires that might carry 12 volts. I wrapped both sides of the
connectors in electrical tape, leaving only the very end of the female connectors open
and leaving the male spades uncovered. This minimizes the risk of grounding out a
connector on the car body and blowing a fuse.
If a multifunction switch is used, wiring is pretty straightforward. Basically, the wires
that come from the passenger compartment get connected to Connector EM02 and that's that.
To tap into the connectors, use terminals scavenged from junkyard connectors of a similar
style. They should snap right into the connector. The connections that need to be made
to Connector EM02 are:
- Pin 2: Connect to the wire coming from one side of the Fog Light Relay Coil
(OEM Relay Pin 5 or Aftermarket Relay Pin 85).
- Pin 3: Connect to the wire coming from the other side of the Fog Light Relay
Coil (OEM Relay Pin 3 or Aftermarket Relay Pin 86).
- Pin 4: Connect to the wire coming from the high current switched output of
the Fog Light Relay (OEM Relay Pin 2 or Aftermarket Relay Pin 87).
If an aftermarket switch is used, the interior wiring is a little more involved.
Here is a diagram showing the wires you'll need to connect inside the car if you're
using an aftermarket switch. All crimp-on terminals are male spades, female
spades, or ground lugs. The switch connector was scavenged from a junkyard, as
were the pins that were added to Connector EM02.
When you're all done, end up with something that looks kind of like this:
Hooking Up Rear Fog Lights (XD and XD2 Hatch Only)
Long before installing my fog lights, I had wired the bright filaments on the lights
on either side of the license plate on my hatch so that they lit up with my brake lights,
giving me five brake lights instead of the usual three (counting the Center High Mounted Stop
Light or CHMSL). When I put in my fog lights, I decided to hook up those lights as
rear fog lights. In Europe, rear fog lights are standard and provide increased visibility
of a car from behind in heavy fog, rain, or snow conditions, which helps reduce the chance
of getting rear-ended. I've seen cars in the U.S. with these lights, including some
Oldsmobiles, Jaguars, Mercedes and SUVs, but they are not commonly found on most North
American market vehicles.
Wiring the rear fogs is pretty easy, but takes some time. Instructions are included for
connecting the lights as both extra brake lights and rear fogs.
Rear Fog Lights as Brake Lights
I'm including these instructions for the sake of completeness, but wiring up the
rear fog lights as brake lights was previously documented in a DIY by
CardassianCruiser on
ElantraClub.com.
This mod involves removing the inside trim from the rear hatch and running a wire from
the existing light sockets and splicing it into the Center High Mounted Stop Light (CHMSL).
There are several screws holding the trim in; once these screws are removed, the trim pieces
are held in with pop fasteners. Generally, pulling straight back on a pop fastener pops it
out. If one or two of the tabs the pop fasteners attach to break off the trim piece, don't
worry, there will be plenty left over to hold the trim in place.
First, the screws. There is a screw at each end of the handle on the passenger side.
Begin by prying off the covers.
Here is what it looks like once both screws and the handle are removed.
Then, remove the screws holding the clips that hold the rear deck cords (one each side)
and the screw at the corner (driver's side only).
Once all the screws are out, it helps to remove the three access panels in the hatch
trim to provide places to grip the trim while pulling it off. Pull of the large trim
piece that had the screws in it. The edges of this piece will be held in by the trim pieces
along the sides of the rear window. As you get up to that end of the trim panel, the
side window trims will be lifted up slightly, which will give you a finger old to pop
them up. Go ahead and remove the side window trimes, then finish getting the large trim
panel off, then trim at the top of the window. There is velcro holding the trim on below the
CHMSL, be careful not to break that.
Once all the trim is off, you can see the lights on the hatch from the inside. there are
two light sockets on each side; one is for the backup light and the other is for the
red marker light.
Unscrew the marker light socket and take out the bulb. There will be two contacts in
the socket. The one wired to a pink wire is the dim marker light filament; the other
one (which has no wire coming out of it) is for the bright filament. If you pull out
the weather seal on that contact, you will see a small length of insulated wire coming
out that is crimped to the contact. On the new piece of wire to be connected to the
contact, slide the weather seal grommet onto it, then strip the insulation off for about
1/2 inch. Then pull the insulation off the piece of wire that is crimped to the contact
and twist-splice it to the new wire. Slide the weather seal grommet back into place on
the connector; it should now look like this:
Connect a wire to each socket like this. Run the wire from the right side of the car over
to the area near the socket on the left and splice them together, and run the wire along
the left edge of the window to the CHMSL. As I ran the wires, I tucked them under the
existing wire harness in several places to hold the new wire in place.
(If you're connecting these lights as rear fog lights, jump ahead to the
Hatch and Door Sill Wiring section to see how to run the new
wire up to the front of the car from here.)
The wires coming from the CHMSL that go to its connector are black and green; coming out
of the connector and connecting to the main harness are black and white wires. The black
wires are ground and the green and white wires are brake light power. Splicing the wire
that was just connected to the bright filaments of the hatch marker lights to the CHMSL
power will make the bright filaments light up when the brakes are applied.
Once you have all the wires run and connected, check the lights out by stepping on the
brake pedal and making sure the lights on the hatch light up; it should look something like
this:
Once you're convinced you've got the wiring correct, tie the wires down to the existing
wire harness where they are loose (I used nylon tie straps for this) and put the trim
pieces back on. Start with the large trim panel, then the pieces on either side of the
window, then the one at the top of the window. Put the pull handle back on and put all
the remaing screws in and you're all done.
Rear Fog Lights as Fog Lights
These instructions assume the rear fog lights are being hooked up in conjunction with
front fog lights using aftermarket switches. If doing this mod to a car with a factory
front fog light switch, the connections will be essentially the same but you'll need
only one switch instead of two.
Hatch and Door Sill Wiring
To connect the rear fog lights to a switch in dashboard, a wire needs to be run from the
rear hatch up to the front of the car. I put this wire in along the left side door sill.
To do this, the door sill trim needs to be removed, as well as the side kick panel trim, the
lower center pillar trim (between the doors), the rear seat bolster, the left side rear
trim, rear quarter window trim, the headliner rear edge trim and the left rear seat belt.
Start at the rear. First, take out the rear seat bolster (the part of the seatback that
doesn't fold). Pop the seat bottom up with the nylon strap on its forward edge and
swing it forward. The bottom of the seat bolster is held in with a 10 mm hex head bolt:
Remove the bolt and slide the bolster up until it comes free of the hook that holds it in.
Next, remove the two rear seat belt anchor bolts with a 12 mm hex socket. The lower anchor
is visible in the picture above; the upper anchor is under a trim cover:
The seat belt tensioner itself does not have to be taken out; just let the end of the belt
dangle for now. Fold the seat back down and remove the rear speaker trim by loosening
the two bolts visible from the cargo area:
And the bolt and screw in the rear seat area:
Then pull the piece up and toward the middle of the car. There will be a slot to slide
the seat belt out. Next, pull off the trim at the rear edge of the headliner. It is held
in with 5 pop fasteners (3 are visible in the picture). Make sure your hands are clean
while working around the headliner (it attracts dirt like no one's business), and
get your fingers under it at one end and pop it off one fastener at a time, working
your way to the other end. Once it's off, remove the push fasteners (one on each side).
With the upper seat belt anchor and the speaker trim removed, the rear quarter glass trim
is held in only by pop fasteners and can be popped off as well.
Now, remove the door sill trim pieces. Each is held in by two push fasteners. The ones on
the front sill trim are pushed in from the side like this:
while the rear sill trim has one from the side and one pushed in from the top. To pop them
off, slip your fingers under the bottom edge of the trim piece and lift up near the fastener.
Once those fasters are out, live the trim pieces straight up to release the pop fasteners
that hold them in.
Remove the center pillar trim by popping the six pop fasteners that are located in the
locations shown. Get your fingers under the top edge and just pull it away from the
pillar.
Remove the screw that holds the side kick panel (between the front sill trim and the
footrest), and pop that off as well.
Finally, it's time to run some wire! Going back to where we ran the wire for the center
brake light mod earlier, the wire has been run from the lights to the top of the hatch
near the CHMSL. I ran the wire through the harness grommet into the main body of the car.
I did this by gently pulling the grommet loose at each end and fed the wire through the hole
the hatch where the grommet snaps in.
Then I used a tip (about 6 inches long) cut off a nylon tie strap as a "needle" and
electrical-taped the wire to it. I threaded the tie strap through the grommet and out the
other end, then into the main body of the car. I then snapped the grommet back into place
and the wire was into the car. From there, it's simply a matter of following the main
rear harness around to the front of the car. Here are some pictures showing the routing:
The routing through the front door sill area is similar. The wire comes out in the
side kick panel area. Notice I left a lot of extra wire; when the rest of the
wires are put in for the switch, this wire can be cut off at an appropriate length.
Once the wiring is run, put all the trim panels back. Start in the rear quarter area. The
rear quarter window trim has to go in before the rear speaker trim and headliner rear edge
trim. Put in the center pillar trim next, then the rear door sill trim. Reattach the seat
belt anchors next, torquing them to 29-40 ft-lb. Then reinstall the seat bolster. Slide
the hook (shown in pictue) into place, then put the bolt back in at the bottom.
Passenger Compartment Wiring
Wiring front and rear fog lights is the same as for front fog lights only, except an extra
switch for the rear fogs is added and a different marker light power source is used because,
as I found out, Diode Z02 connected to EM02 Pin 2 is not adequate to power the rear fogs.
If that pin is used, Diode Z02 is likely to burn out and the fog lights will not work. I
found an unused (and undocumented) marker light power source on the Passenger Compartment
Fuse Box, on Connector I/P-B, Pin 13. This power comes from the same fuse as EM02 Pin 2,
but comes does not go through a diode.
The schematic will be similar to the earlier schematic for front fogs only, except for the
addition of the rear fog light switch and using I/P-B Pin 13 for marker light power instead
of EM02 Pin 2.
Connector I/P-B is on the Passenger Compartment Fuse Box just below the fuses, but it is not
accessible through the fuse box access. To get to the connector, the lower kick panel and
the metal structure behind it need to be removed. First remove the two 10 mm hex head
bolts at the bottom corners of the kick panel:
Next, remove the coin bin:
Reach in through the fuse box opening to pop off the trim piece on the end of the
dash (poke it from the inside with your finger):
Then remove the two screws that were hidden by the trim piece:
The kick panel is held in place with two pop fasteners on either side of the steering
wheel. Pull straight back to pop them off. You can see the pop fasteners in this
picture:
The kick panel is off, but the OBD-II connector and the hood release cable are still
attached to it. Release the cable by pulling back against the cable, then sliding the
cable out of the conduit end holder by moving the panel toward the center of the car,
then sliding out of the hood release lever by moving it back the opposite way.
It's hard to explain, but maybe the following picture can help illustrate. There is
a slit in the conduit end holder that the cable can slip out of:
That picture also shows the two screws that need to be removed to separate the OBD-II
connector from the kick panel. Once the cable and the OBD-II connector are disconnected,
the kick panel can be completely removed. Next, remove the metal support behind it to
access the fuse box.
Now Connector I/P-B is accessible:
Now that you can get to it, insert a wire with a terminal at Pin 13 and wire the rest
of the connections like this (for front and rear fogs):
Detail of switch pannel connections:
The way I have the rear fogs wired, they only go on if the front fogs are on. I did this
so that the indicator light will be on whenever there are fog lights on. In general, rear
fogs look the same as brake lights, so I only use them when there are truly severe weather
conditions, while I use the front fogs more frequently.
If your Elantra has factory fog lights in the front and you want to hook up just the rear
fogs, wire it up like this. Note that power is still being drawn from I/P-B Pin 13, and
that there is no tie-in to the instrument cluster indicator light:
When you get everything wired up, it will look something like this. The first picture shows
rear fog lights off, the second shows them on.
When wired up as shown, these center hatch lights operate independently of the brake lights.
