Gmc Envoy drivers side brake light dont work replaced the tail light circuit board it worked for about 3 wks now its out again! all of the lights work except when u hit the brakes the drivers side doesnt. Thanks

ST/LP, Fuse 12, 25 Amp - feeds battery positive to brake switch ORN (orange) and out the WHT (white).

Test with a simple automotive incandescent test lamp to ground. Test lamp should light on both sides of the fuse and with contact to the switch ORN and to WHT while brake depressed.

The tail light fuse is under the rear seat on the drivers side.

Start with changing bulb

feed supply problem somewhere ?but where ? try checking the wiring loom at the rear or as its called in american "pigs tails"

First let's determine which brake lights are not working. Does the high mounted brake light work? Do both left and right brake light not work? If none of the brake light work, the problem could be the brake light switch at the brake pedal OR fuse #12 in the underhood fuse panel.
If only the bake lights at the corner lamp assembly don't work, check fuse #34 in the rear fuse panel.
The module your are referring to is the circuit board located in each of the corner lamp assemblies, check on website www.compnine.com for the part number of this item. I don't believe this is your problem though.

First and easiest we need to check for power going to the rear lights at the plug that goes into the tail light housing. There is a board that the lights plug into that goes bad. The Envoy uses separate brake and turn bulbs so the 3rd brake and the two side are on the same circuit.

Sounds like you need to replace the drivers brake/tail light.

check globes and check brake light switch under dash on brake pedal.

FYI - there was a recall on the GMC Envoy tail light circuit boards back in 2004-05. I would suggest taking it to an authorized dealer and ask them about it. A lot of times these types of things are taken care of at no charge if it is/was a factory recall. It's a safety issue - they should take care of it.

theres usually a pressure switch behind the brake pedal, sometimes the plastic hex nut rattles loose and you have to retighten it.