1991 BMY m923A2 wire #642?

[Meanguy]

I was working on my horn today when i noticed a wire starring at me from behind the steering wheel shaft. It looked frayed like it had been yanked loose from a connector somewhere. Its wire designation # is #642. Upon completing my horn work and reconnecting my battery i engaged my battery switch and checked the wire for voltage. It had 12v running across it. I have scoured over the barely legible wire harness schematic in the TM and cannot find this wire designation #. It could be i am just not able to read some of the numbers or just am over looking it somewhere. Does anyone have a clue what this wire is for? Truck runs just fine, only gauge i have that is not working properly is the engine temp gauge. I dont use my lights at all so it could be somewhere in the lighting system that i would have never noticed not working? Any pointers would be welcome.

Meanguy

 

[rhurey]

Blower low speed work?

 

[Meanguy]

I will check that next time i start him up, thanks for the tip! I will go back over the TM diagram and look at that specifically.

 

[Meanguy]

The TM lists 569 as the 12v source wire for the blower, I will however confirm this on the truck.

 

[Swamp Donkey]

I'd go to the battery box and see if you find the other end in there. Really only one way to get 12v off these trucks in stock form and that is to pull from one battery, like the #569 wire for the blower motor.

I don't see that wire in the diagrams either. Mine are the High Definition version. I do see that the 600 series of numbers is only on the M934 trucks on those diagrams, but I don't see a #642 there either.

These numbers are part of a standardized system across multiple vehicles to quickly identify circuits. Olive Drab has a list which breaks down these numbers to show the circuit where they are located. #642 comes back to "booster motor power", whatever that is...

Are you sure it's #642? I've misread more than one of those tags due to paint and corrosion.

 

[Meanguy]

OK, so you were so correct SD, upon brushing the metal tag with a wire brush i have found it says 6427-3. This does not make any more sense to me than what i previously thought it said however i wedged my head up under my dash as far as i could to try and locate the other end of the wire and although i did not find it it does seem to hang straight down from somewhere directly above. I will have to do more investigating tomorrow in the daylight. Here are some images i was able to get of it.