Hi, no brake lights on my 3500 Gmc, swaped relay under hood with another truck, didn't work. Can't reach stop light switch to test power so swapped out switch with working truck, didn't make a difference no lights. Checked wireing from connector at fire wall to lights, all good was able to power up lights. Where do I go from here to find out if my interlock solenoid is bad if the brake light system is not working. Am I missing a relay or switch somewhere? I also checked fuses, and all other light systems are working fine (hazards, blinkers, park and drive lights. Thanks Brian
Check and test the stop lamp relay and the turn and hazard switch-the brake circuit goes thru there
March, 9, 2011 AT 6:11 PM
I've checked the 3rd brake light, it does not work either. I have swapped out the relay under the hood with a working one from another truck and it made no differance. I have working turn signals and hazard lights, also have parking lights. Is there another relay somewhere other than under the hood? Also would the power for the brake light go to the turn signal switch first and then to the stop switch? Thanks Brian
March, 9, 2011 AT 7:05 PM
You're going to have to test for power coming in and out of the brake light switch.
February, 1, 2013 AT 9:01 PM
Just fixed my 2000 gmc 1500
orange wire under the fuse box under hood was corroded and broken.
Was told to look for a orange and or a white wire.
Fixed wire and lights and my cruise returned.
Hope this can help.