Question about 1993 GMC Sierra
Your description, I take it, is a problem with the wiring harness going from the driver's compartment to the rear lights. If that is the case, the normal color code for GM is brown for tail lights, dark green for the right stop & turn, yellow for the left stop & turn and light green for the backup lights. Any black wires should be grounded. The white wire in the trailer harness is for a ground when used on a trailer. It sounds like you have the green and yellow T&S wires shorted together somewhere! Some of the later vehicles use separate stop and turn bulbs... these would have a separate wire for the stop lights only, but I don't think your truck is new enough for that. Good luck!
Posted on Nov 25, 2013
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Posted on Jan 02, 2017
I had the same problem but when i tested the left turn signal then tested the brakes both brake lights would then work.
Posted on Mar 04, 2009
I did 15a and electrical for over 30 for chevrolet and seen some pretty weird stuff.To me you still have a ground problem.your idea of checking the brake light switch is a good start.both rear lamps flashing to me means the hazards are shorting across the turn and brake light circuits,because hazards stop flashing when brakes are applied.The brakes light switches in the 90's were really weird because they also incorporated the abs system.Good luck,let me know what happens.Thanks
Posted on May 26, 2009
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
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