Hi all.

I have a 94 g30 that’s been converted into a school bus. I’m having some brake light issues. I have never had working brake lights on this thing. I installed new led brake turn reverse combo lights. Turn reverse and running lights work but no brake lights. I’ve replaced the brake switch, the dimmer switch and the turn/hazard switch. I’ve cleaned the engine block ground. Is there a relay or other switch that might be the issue?

thanks!

 

Are there only 4 wires that control rear lights?

I have isolated the wire that lead to rear lights.

yellow
brown
dark green
light green

all wires get voltage for various functions except brakes. No wires get voltage when I hit the brake pedal.

 

If you intend to do repairs on this van yourself, I highly recommend picking up some wiring diagrams, like a Haynes repair manual. Well worth the money.

 

Is there a brake relay somewhere? If so, generally where is it located. I’ve torn the dash out trying to track this down and I found a relay tucked behind the gauge cluster. Is that brakes or headlights?

thanks!

 

Reporting back on this, I solved the issue.
this is a bus conversion with a telma magnetic brake system. A wire from the turn signal switch was cut to signal the telma system. I repaired the cut wire now I have signal going back to the rear lights.