Installing factory fog lights on a non-fog truck

Steventruck · Post by **Steventruck** » Sat Apr 29, 2006 4:57 pm

I will attempt to explain the process of installing factory fog lights to a S-10 that was not originally equipped with them.

My truck had the relay and fuse for fog lights in the underhood electrical center and was pre-wired for the switch behind the headlight switch so I just added the missing parts.

STEP ONE: CHANGE THE SWITCH

You will need to change the headlight switch the one with the fog button.
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The installation of this switch is pretty straight forward because you simply remove the old switch and replace it with the new one. To change the headlight switch:

Remove the two upper screws on the panel by the driver's knees.
Remove the screw above the instrument cluster and one screw on each side of the column.
Firmly pull the upper dash to remove it from the spring clips. Be careful around your hazard switch as it breaks easily.
Unplug the headlight wiring, 4x4 wiring, and airbag disable wiring or rear wiper wiring.
Use a super tiny socket or needle nose pliers to unscrew the four screws that hold on the switch.
Installation is the reverse of removal.

STEP TWO: CHANGE THE B.C.M.

I found a GMC Jimmy in the junkyard that had the factory fogs. I bought the BCM for use with this project. You will need to reset the passlock for use in your vehicle.

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Instructions for swapping the BCM:

Remove the trim the covers that bottom of the dash. The BCM is located in front of the floor console (if so equipped) near the floor in the center.
Unplug the three connectors, starting with the top one.
Remove the BCM by pulling firmly on the top of the box, you may have to jiggle it around slightly to release the tabs.
Install the new BCM, plug in the connectors, and replace the panels.

At this point, you should be able to turn on the parking lights, then push the fog light switch and it will work, but you won't be able to start your truck (Passkey disables the fuel injectors if the wrong key is used). To get your key to work, attempt to start the truck (it will crank, but is will stall out after a few seconds). Leave the key in the ON position. The SECURITY light will be flashing. Wait for it to stop flashing (about 10 minutes), turn the key OFF, then attempt to start. It should run.

STEP THREE: ADD THE LIGHTS

This is the part where the look of your truck starts to change. This is just swapping out the parking lights on your truck for the fog light versions.

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Instructions for swapping lights:

Raise the hood.
Firmly pull the grill toward the front bumper to release the spring tabs.
Unplug the lamps from the lamp housing (the reflector/lens assembly)
Unclip the original parking lights and install the new ones with the fog light housing.

At some point, you will need to aquire the lamp bases as they are not prewired on the truck. I used lamps and bases (with 10" or so of wiring) from the junkyard. These can be from any late model GM fog light. If you are fortunate enough to get the front wiring harness, you can skip most of step four. If not, run the lights in parallel (Y both purple wires, each black wire can go to ground directly or tapped into the ground for the parking lights).

Re-assemble everything.

STEP FOUR: POWER THE LIGHTS

The truck is now wired up to the underhood electrical center (UHEC). The relay clicks with the switch, but the relay isn't powering anything. This step will fix that.

Open the hood
Disconnect the negative battery terminal.
Stand on the left side of the truck looking at the engine... you should see this:

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The black box at the bottom of the picture is the underhood electrical center. It should be labeled as such.

Remove the cover
Disconnect the large red power input wire on your left side of the UHEC (7mm)
Remove the three 10mm screws holding down the UHEC.
Pick up and rotate the box away from you so that you can see the bottom.
Unscrew the lock screw from the GREEN connector and remove.

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The pin that I'm pointing to (E2) is the pin that powers up with the fog lights. This needs to get connected to the purple wire going to your lights. I had some random connectors around. I installed the female part into the green connector at the appropriate place.
Re-assemble, making sure that the negative terminal at the battery is the last thing you connect.
Test to insure that your lights are now working.

If you got a front end body hardness, remove your old harness and plug in the new one.

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I also replaced the lamps with new one. Stock is either 880 or 881 (27w). I used 885 (50w straight base)

Enjoy

Steve

Linked over 100k limit images. Cut those down to half that size and you might have something here -HJ

jeff024 · Post by **jeff024** » Sun Apr 30, 2006 1:22 am

great write up.
But I hate to switch gears here but I noticed your cab lights and I have been thinking about think we could see some better pics of them?