1972RedNeck

My truck has a few electrical problems. The anti lock brakes, the speedometer, and the cruise control don't work. The ABS and Brake light are always on. I can't control which set of vents the air goes to (it's stuck on a/c / vent). I have installed a new speed sensor at the t-case.

I'm stumped. I can fix mechanical, but the electrical causes my brain to short.

j_martin

Vent control is by vacuum. If you try to solve that as an electrical problem, it's bound to give you a headache.

Have you worked on your brakes lately. It's pretty common for either the switch on the parking brake, or the brake warning switch on the balancing valve to set the brake warning light, which automatically sets the ABS warning light. Either one can be eliminated as a cause by simple disconnecting them. A fault in either placed disables ABS.

Depending on your truck year, and mods, you may have a PCM or sensor issue.

dodgenstein

There is a low vacuum sensor below the driver's side hood hinge. This will trigger the brake warning lights. Since the HVAC isn't working correctly, I would first check for a problem in vacuum circuit and also check for a broken nipple on the vacuum sensor. It (the sensor) has a small plastic nipple attached to a hose that can be snagged and easily broken.

1972RedNeck

Can somebody get me a picture of the vacuum sensor? I don't know what I'm looking for.

The line going from the booster to the cab was melted. There is a couple of ports on the firewall for vacuum lines. All the hoses are pulled off. Where does each hose go?

1972RedNeck

No?

j_martin

Go buy a service manual on CD at Jeno's, then you can just look it up instead of getting peeved.

1972RedNeck

Thanks,

I'll get the cd ordered.


What do you all think about my cruise and speedometer? Where should I start checking?

MARF75

the cruise could be vacuum related too?

1972RedNeck

I don't think the cruise is going to work until the speedometer works. I could be wrong though.