My dad just bought a 94 1ton 5 spd, and the tach and speedo doesnt work on it. The previous owner said they both quit at the same time. The grid heater isnt working either but have no idea if thats even related yet. I havent had any time to check it out yet. They swapped ecms, sensors and gauge clusters but had no luck. Anyone experience the same trouble?

 

does it charge properly? if not check the crank position sensor. if it is bad it causes a no or low charge and no tach situation.

 

If you also aren't charging it's the engine speed sensor (ESS) at the lower engine pulley.
Check that wiring to it is intact and that the gap between the sensor and pulley is about the thickness of a business card.
The ESS does wear out, may need to replace.

 

Also make sure you have power to the ESS.

 

I thought he said it was charging, but turns out it isnt. I will check the sensor and wiring. thanks everyone

 

The truck is not charging either. We swapped altenators, crank pos sensor and the pcm or ecm whichever it is called on a 12v. Nothing has changed, still same problem. i checked for voltage at the cps with the truck running and there is nothing there. any ideas?

 

Bad connection or broken wire.

 

did you check all the fuses? both in the PDC (power distribution center, big fuse block under the hood) and in the side of the dash?

 

Check fuses with a meter or test light, just looking at them doesn't always work.

 

Well, we finally swapped wire harnesses, but i think its too late. I think we need a new pcm. Its gettin 12v from the ign. but not getting the 5v to the cps.