Im at a loss with my brake lights

[pattison87]

Im not sure if this has been covered yet but i havent found a situation like mine so i figured i post it. My driver side brake light is intermittent. I havent figured out why. My passanger side BL works fine with no issues. Ive checked the grounds and changed the the bulb housing and still no fix. Tried a new bulb and still nothing. Both the rear lights work when turning the lights on, but the brake light still is intermittent. The LH blinker only works sometimes as well. It either flashes like normal or just stays solid. And another thing is when i push my brakes with the hazards on the hazards stoop flashing. Anyone know why i cant get both brake lights to function properly? Thank you.

 

[chengny]

The entire rear lighting harness is grounded on the RH side. The lamps in the RH cluster are very close to the ground point, but the ground wire from the LH cluster has to cross over to it.

Inspect the black wire that leads from the LH lighting group and travels along the cross frame over to the lighting harness ground point.

The power to both brake lights is on a common lead up to the weathertite plug. If it was only the brake lights that were acting up the first check would be the hot wire from the plug to the LH cluster.

But since there are intermittent problems with some of the other lamps in the LH cluster, that would indicate a fault in the ground wire which is common to all those lamps.

 

[pattison87]

Recently had leg surgery so ill get to it when i can. Thanks for the reply. So just make sure the RH and LH ground are connected? And i forgot to mention when i had both sides grounded both sides would work but the lights themselve were very dim and did not get brighter if the break was applied. Still at a loss. Ill try your solution though.

 

[chengny]

To confirm/eliminate the LH cluster common ground wire as the problem you could try creating a dedicated ground connection for that group. Just solder a branch wire into the black lead where it comes out of the RH harness. You can cut the wire where it starts to lead over to the other side (or just splice into it) and attach your new ground lead to a clean (bright metal) spot on the frame or body.

Also, I am starting to second-guess myself on which side the rear lighting harness is grounded on. As a matter of fact, my truck has ground connections on both sides of the harness.

 

[pattison87]

Mine was just grounded on the left hand side. So i tried switching it to the right hand side and same problem. And then when i ground each side( seperately, not with a single ground wire) the lights did the dimming issue and i had no brake lights at all.

 

[chengny]

Wow! That is a head-scratcher.

 

[Boone83K10]

This sounds kind of like the problem I had. Did you look up stream for any melting of the wires?

 

[pattison87]

i only tore into the plastic loom until i found the ground on both sides. I didnt see anything up to that point. I also didnt see anything wrong with the whether tight connector. BUt who over had the truck before me spliced into wires for a trailer plug but i kinda looked over it and nothin seemed to be grounding out or not connected. I should probably recheck that again. Did you figure it out Boone83k10?

 

[Boone83K10]

yes...see here ---> http://www.gmsquarebody.com/forum/showthread.php?t=7823&highlight=brake+light+problem

either read whole thing or start at post #42