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04 Sierra - Help! No brake lights or tail lights, but signal lights are fine??


carcrazysincebirth
11-06-2008, 06:25 AM
I have a 2004 GMC Sierra crew cab with a 5.3. Last week I noticed that the right tail light was out. I picked up a bulb, but the old bulb ended up being fine. I figured it might be moisture, so I sprayed some penetrating fluid into the socket, but still no light. After a couple of nights, I checked to see if the right tail light was working yet, but was surprised to see that neither tail light was working. Besides that, the brake lights are not working either, except for the 3rd brake light mounted over the rear window! Since then, I checked almost every fuse inside the driver's door and under the hood. No burnt fuses! I looked to see if anything was jammed into the factory trailer hitch plug, but it looks clean. I looked up at the light module under the rear bumper to see if any wires were hanging, but nothing stood out. Can somebody help before I get over-charged again at the local dealership??
Thanks

maxwedge
11-06-2008, 01:59 PM
I'd see if you have 12v in the tailite circuit up to the module for starters.

463
11-07-2008, 09:55 PM
check the factory trailer hitch plug to see if there is power . here is the dia.IV. 6-WAY & 7-WAY CONNECTOR WIRING DIAGRAMhttp://www.easternmarine.com/em_store/tech_info/tech_images/wiring2.gif
III. 4-WIRE SYSTEM WIRING DIAGRAM

SPECIAL TIPS
Avoid routing wires over sharp edges or pinching them. All splices should be sealed with flexible-waterproof calking for extra protection.http://www.easternmarine.com/em_store/tech_info/tech_images/lighting_dia.gif

463
11-07-2008, 10:11 PM
you might want to take a good flashlight under the truck and take a good close look at the wires from the back to the front of the truck. ps my son had his car in to the gm dealership for a fuse that kept blowing. $550. cdn (electrical rate was $110 per hour ) and they could'nt resolve the problem. so home he came to get me to fix it. turned out to be the steel shovel in the trunk that cause the wires to short out.

kevinc70
12-21-2008, 05:39 PM
I had the same problem it turned out to be one of the square fuses under the hood. Not sure if it is a fuse , it looks more like a relay or flasher but I change mine and its worked ever since.

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