Appears to be no power to Brake Lihgt relay under hood
The 1996 GMC Yukon brake lights work by receiving power from the brake light relay switch. The brake light relay switch is connected to the brake pedal.
The GMC dash tail and parking lights are on a different fuse from the brake lights. Check the fuses for a possible blown fuse.
Although both signal lights and stop lights are within the same lens, they operate on different wiring. The bulb will usually have two filaments, one for stop and one for signal. If the brake lights are not working, the problem is probably a blown fuse or a faulty break light switch.
Brake light switch failure, bad ground wire at rear of vehicle or fuze blown.
Check the fuse for the brake lights. It should be marked stop/haz on the fuse box cover.
If you do not have working tail lights on your GMC vehicle it may be an issue with the wiring or your lights may be burned out.
Riunning lighs not working 2002 gmc envoy
1994 gmc no brake lights 3 brake light works need help
The brake lights on a 96 Jimmy are operated by the brake light switch, mounted on the brake pedal assembly. If the switch is bad the lights could stay on or off, or be sporadic.
The 1996 GMC Sierra DRL module is located underneath the dash panel on the driverside between the pakingy brake pedal and the brake pedal.
I have a 1983 GMC Sierra it has no dash,tail lights an brake lights are very dim
If there is a trailer wiring harness on the vehicle for towing unplug harness under drivers side rear tail light to eliminate the trailer wiring that's probably the issue then plug factory wires together