Mbl35 Posted April 13, 2010 Share Posted April 13, 2010 08 Chevy box ambulance 6.6 durmax. The brake lights are on constantly. I unplug the brake light switch-still on. I unplug the ambulance body brakelight diode-still on. I can't find the chevy manuals-i think they're at our other shop. Is anyone familiar with the brake light circuit on these? Possibly a relay somwhere that im missing? A shorted multifunction switch? Quote Link to comment Share on other sites More sharing options...
cbriggs Posted April 13, 2010 Share Posted April 13, 2010 OK, according to mitchels wiring diagrams, the brake switch has one normaly open and one normaly closed switch. The normaly closed switch(org/wht and ppl wires) signals directly to the body control module, the normally open switch (lt blu/wht and pnk wires) signals the pcm, tcm, trailer provisions,as well as the body control module. The rear brake lights are direct outputs of the body control module. Im thinking you may have an open in the normally closed switch section or wiring, and unplugging the switch would not reverse that. Try jumpering the org/wht and the ppl wires and see what happens. Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted April 13, 2010 Author Share Posted April 13, 2010 ok thanks. Quote Link to comment Share on other sites More sharing options...
OHNO60 Posted April 13, 2010 Share Posted April 13, 2010 hey Mb, sometimes the ambulance manufacturers use their own relay in the module. what brand of ambulance is it? Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted April 14, 2010 Author Share Posted April 14, 2010 I think Medix. We used to have a manufacturer schematic book for every unit. They all disapeared when we moved. Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted May 7, 2010 Author Share Posted May 7, 2010 We got it back from chevy, the brake light concern repaired but now the headlights and interior lights are inop Quote Link to comment Share on other sites More sharing options...
Aaron Posted May 8, 2010 Share Posted May 8, 2010 Well, that's not what you had it there for, you get either one or another. Does the Chevy use the BCM to run the lighting, kind of like a GEM on a Ford? Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted May 8, 2010 Author Share Posted May 8, 2010 yes. But i never got a chance to review the work summary to see what repairs were made, it's been so busy. If i could get a chance, i would sit down with the wiring schematics. We got the gm repair manuals and tec2 now. Quote Link to comment Share on other sites More sharing options...
Mbl35 Posted May 13, 2010 Author Share Posted May 13, 2010 Anybody know where the turn signal/hazard/flasher module is located exactly on this? The book shows it's next to the chimer module in the center of the dashboard. I took the whole thing apart and there's nothing there. I tried to use sound to locate them but the chime and blinker sounds come through the speakers. Quote Link to comment Share on other sites More sharing options...
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