tach spins backward

[markjdinger]

I recently had a shop tell me the pcm was bad on my 94 xlt 4 wd, 5 speed.
It was fine when I took it in to get the clutch replaced. After the clutch replacement, they said it ran like crap and need a new pcm. They replaced, and since, the tach has spun backward (counterclockwise). When questioned, the shop said the tach needed to be replaced. They claim it has nothing to do w/what they did.

I've searched and can find no posts on what may have caused this.

Anyone have any ideas.

By the way, used this forum to re-build my shift motor and auto hubs. This site is fantastice.

 

[markjdinger]

update to backward spinning tach

My tach no longer spins backward. It doesn't do anything. This summer when the temp approached 100 and I drove the about 20 minutes, the tach would start working perfectly.

Obviously has something to due with heat and something expanding enough to either make an electrical connection or some physical connection.

Since I'm not sure where the tach gets its reading, not sure where to troubleshoot.

 

[YourNameHere]

Not sure what it is, but if it turns out the shop caused it, I'd be handing them the bill.

 

[wood1]

You could try two things...

strike it smartly with a large basheometer,

remove the tach and check it for broken solder joints.

Good luck!