M1028 No Lights/Wiring Issue

[fireman5214]

Hello all,

Our CUCV M1028 at the fire company has no lighting that works, brake, reverse, turn signal, 4 way, headlights, parking lights. Me and my dad bypassed the toggle switches for the blackout lights on the lower left side of the dash with a paperclip and everything worked except the brake lights and reverse lights. We took both switches out and tested them with a meter and the switches are good. As soon as we put it back the original way, they dont operate. My dad assumes there is a relay but we can not find it anywhere. We even looked through the TM's and cant find what we are looking for. I went through all of electrical TM9-2320-289-34P and we looked at electrical, but then in troubleshooting it helped a bit more on the blackout lights but not much on TM9-2320-289-20. If there is a relay, where would it be located? Any other wiring diagrams out there that could help us in this matter? We would like to get this truck in service for our fire company.

Thank-you in advance!

 

[Recovry4x4]

In the 289-20 you will find schematics in the appendix. These should really help.

 

[fireman5214]

In the 289-20 you will find schematics in the appendix. These should really help.

Yeah, we tried that and it didn't really help unfortunately. Do you know if there is a relay in the dash somewhere? Or is it just a bad ground somewhere?

Also what is defined as the "service lights" on the truck?

 

[nyoffroad]

Service lights are all the 'normal' lights, tail/marker/stop/turn/headlights. That switch needs to be in the up position all the time.

 

[sneekyeye]

Just a wild idea thrown out at this point , but perhaps it's a ground issue under the dash.
It might explain the lack of lights when the switch is on and when the brake is pressed.
I don't have the wiring diagrams in front of me, but the fuse panels are somewhat bad about having bad connections
at the fuses themselves. Check and see if the fuse for the lights even has power to it and to the switch.

 

[fireman5214]

Hello all, we diagnosed it and it was indeed the relay that was bad behind the speedometer. Replaced that and the lights work. The only things that dont work yet are the brake and back up lights. We found out that the back up lights were disconnected and the part that is in the steering column is missing. Now we are on to fix that and work on the brake lights. We forgot to push the brake pedal and see if the relay also fixed the brake lights, we can try that some other day and I will reply to this thread.

As for all the others that have chimed in, we appreciate your help and support! Thank you!