Help Rewiring Brake and Turn Lights

[dreammachine]

I have a '89 Ford B700 with a Carpenter body and 6.6L turbo diesel. The brake lights haven't worked for probably 5 years, and recently the turn lights and warning flashers stopped working. I talked to some people who said I'd be better off rewiring than trying to find the problem. There are some aftermarket wires that were installed to add trailer lights to the back of a back porch that complicates the circuitry a bit.

Turn Lights/Flashers:
I used a multimeter to check the fuse and the chassis plug rail. Both are getting electricity when I checked them with the turn switch turning left. However, there is no clicking noise like there normally is when using the turn signal/flashers. I thought that perhaps the switch on the steering column stopped working, but since the fuse and the chassis plug are getting power, I don't think that's the case. So what component makes the turn signals flash, and is there where I should start by trying to replace it?

Stop Lights:
I would really like to get these working but I am lost as to where to start. My friend checked the mechanical switch on the brake pedal and that is still working. I checked for voltage in the plug to which that switch connects, and there is no power. I also checked for voltage in the fuse box and chassis plug, and also no power. I am uncertain as to how the stop lights are wired up front, though I do have a wiring diagram for the back of the bus. Does anyone know the basic wiring of stop lights up front? Like power supply -> switch -> fuse -> chassis plug or is it more complicated than that?

I have been driving around using the running lights as stop lights in the daytime, as well as using them for warning flashers going up steep passes.
I would like to get this fixed for safety and peace of mind. Any help is much appreciated!

I can post a wiring diagram from the chassis plug back a little later if that helps.

Thanks,
Alan

[Sleddgracer]

Originally Posted by dreammachine

I have a '89 Ford B700 with a Carpenter body and 6.6L turbo diesel. The brake lights haven't worked for probably 5 years, and recently the turn lights and warning flashers stopped working. I talked to some people who said I'd be better off rewiring than trying to find the problem. There are some aftermarket wires that were installed to add trailer lights to the back of a back porch that complicates the circuitry a bit.

Turn Lights/Flashers:
I used a multimeter to check the fuse and the chassis plug rail. Both are getting electricity when I checked them with the turn switch turning left. However, there is no clicking noise like there normally is when using the turn signal/flashers. I thought that perhaps the switch on the steering column stopped working, but since the fuse and the chassis plug are getting power, I don't think that's the case. So what component makes the turn signals flash, and is there where I should start by trying to replace it?

Stop Lights:
I would really like to get these working but I am lost as to where to start. My friend checked the mechanical switch on the brake pedal and that is still working. I checked for voltage in the plug to which that switch connects, and there is no power. I also checked for voltage in the fuse box and chassis plug, and also no power. I am uncertain as to how the stop lights are wired up front, though I do have a wiring diagram for the back of the bus. Does anyone know the basic wiring of stop lights up front? Like power supply -> switch -> fuse -> chassis plug or is it more complicated than that?

I have been driving around using the running lights as stop lights in the daytime, as well as using them for warning flashers going up steep passes.
I would like to get this fixed for safety and peace of mind. Any help is much appreciated!

I can post a wiring diagram from the chassis plug back a little later if that helps.

Thanks,
Alan

sounds like your flasher unit died - small round canister looking thing, about 2 1/2 - 3 inches long - often found under the dash - not very expensive - I've had to replace 2 or 3 of them over the years - no clicking is a clue to the flasher unit being unserviceable ( that reminds me of a short story - when I was in the Air force many moons ago, when a piece of equipment wasn't working, we'd write U/S on it ( short for unserviceable ) when we'd have a fly in to a US base on temporary duty, the airmen there would ask why we wrote U/S on the equipment - they weren't happy when we explained - lol

[BlackJohn]

Well the brake lights appear to be unfused for one thing and no flasher in its socket for some reason. Lots of cobwebs and moisture happening in that fuse block.


John

[Sleddgracer]

Originally Posted by BlackJohn

Well the brake lights appear to be unfused for one thing and no flasher in its socket for some reason. Lots of cobwebs and moisture happening in that fuse block.


John

makes me wonder if there was an existing problem and the blinker was removed to 'fix' the problem

[dreammachine]

Sleddgracer I think youre right about the turn signal flasher. I saw a component when snooping around that said Must fuse x lead. Just looked it up and that's it! I'll get a replacement and test her out ASAP. Thanks!

As for the brake lights, thats gonna be a bigger mystery. I'm getting frustrated by all the redundant and confusing names in the wiring diagram. I thought for sure stop lights were the brake lights but it seems that stop lights are the school bus flashers when dropping kids off.

As for the cobwebs and rust, unfortunately the firewall and hood have been leaking water. I tried patching them with silicone caulk but there is still water. :/

That may be the root cause of the electrical issues I'm having. If it is, ive no-one to blame but my own negligence.

[dreammachine]

Is there a way I could rewire a hot wire with fuse inline to the brake switch and see If That fixes the problem??

Or even rewire the whole brake light line?