Hello,
I have an automatic ‘02 GMC Savanna 3500 (Skoolie) that was converted into a concession bus with a breaker box, sink, etc.
I noticed that the brake lights - or rears in general - haven’t been turning on. The signals, however, do work. I checked all fuses, we replaced bulbs, and nothing works.
Do any of you have any recommendations on where I could start looking or know what the possible cause of this could be?
***This is only for rears, all lights work in front***
That thing is 24 years old and has had significant custom modifications. There could be any number of problems with the electrical system.
You could check the grounds for the rear lights as well as for any corrosion in the bulb sockets. Also check operation of the light switch and relays. Other than that it comes down to doing basic electrical troubleshooting with a multimeter or test light to find the fault(s).
You can find a repair manual for that truck at the link below which will have wiring diagrams as well as information on ground points, modules, and relays:
