Question about 2003 GMC Yukon Denali
I've had problems with my 2003 Yukon XL Denali trailer lights for years. They seem to have originated when I hooked up a dump trailer (with LED running, stop and turn lights) and the lighting control module began to smoke. After replacing it, everything was okay for a while but now there's no right trailer turn signal ... not even an electrical signal coming into fuse box. I have 3 trailers and they work fine with other trucks so I'm pretty sure the problem's with the Denali. I'd replace the lighting module again but would like to addresses the root cause before spending the time and another $100 for a temporary solution. Thanks in advance for your help.
Posted by Anonymous on
LEDs overload the original flasher relay.. replace it
if no better
run a new wire for the right trailer turn signal
and check the earths
Posted on Mar 31, 2017
Check a few things...
- The bulbs
- Check for ground at brake lamp connectors
- Check your wiring at the connectors for power
- Check for another fuse blown
- Do not hook up the trailer until you fix the ground problem on the trailer
- On some models, there is a module to control the rear/trailer lighting system. There may be a problem in the module.
Posted on Jul 24, 2009
There is a 4wd module which should be located above the glove box area. Listen for a click while shifting into 4wd from that box. If no click, look there first. Also look at the multi-pin connector on the transfer case. They are very small pins which will, if bent, wont sit properly.
Posted on Aug 17, 2009
Check the plug at your gmc outlet, your right signal wire has been damaged before the plug somewhere. If you have a test light switch your right signal on and make sure it is working at the plug on your gmc, you will find it is not working, than trace the wire back from the plug till you find where it has been damaged or you can run a wire straight from plug to your right signal.
Posted on Jun 09, 2011
SOURCE: Have issues with trailer lights.
Standard wiring colors are as follows: 4-Way 5-Way 6-Way 7-Way Green Yellow Brown White Red Blue Purple Right Turn & Brake Left Turn & Brake Tail Lights Ground Backup Lights Electric Brakes Auxiliary Power
Green- Right Turn and Brake
Yellow- Left Turn and Brake
Brown- Tail Lights
Red- Reverse (Back Up) Lights
Blue- Electric Brakes
Purple- Auxiliary Power
It sounds like your green and yello wires are shorted together somewhere along the length of the harness. I would check the wires on the trailer first. Easier yet, if you have another trailer to connec or access to another to use for testing, connect to it and see if the problem repeats; if it does the trouble is in the vehicle's wiring.
Right Turn & Brake
Left Turn & Brake
Posted on Jun 26, 2011
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