Tach problem help requested on 86 Carrera
 

Hi All,
I know this has been discussed before, however I'm looking for a bit of advice-

Car: 86 3.2 Carrera Coupe

Issue: Tach will be reading perfect, then suddenly drop to zero. Stay there for a while then jump right back and work perfectly. This comes and goes. It will work fine for 30 min. or 2 hrs., then drop to zero for 2-3 min. then jump back and read perfect again. It has been doing this for about 2 years now and is driving me crazy. (It does not fly around erratically, either perfect or zero.)

I crawled under the car to check the ground strap on the tranny and it does seem secure and realatively clean (I had the tranny out a year ago so I assumed the wrench cleaned the connections but maybe not). I did notice a spot on the strap that seemed to be wearing a bit, but everything appeared solid.

I R/R the alternator/voltage reg about 3 months ago and it is working perfectly.

What should I do next?

I understand the tach receives it's juice from the DME (?). Are there connections I should check/clean? Should I check the connection at the Tach itself. Should I remove the Tach and send it to be repaired? Should I remove the tach, use a volt meter while driving to see if I'm getting a constent volt feed?

I spoke with one wrench to said it was probably the Tach itself, but why would that be the case if it works perfect 80% of the time.

Does anyone have a check process or series of checks to go through prior to sending the Tach off for evaluation/repair?

Thanks much for any and all help!

Pull the tach out and check the connections on the back. You should also check the connections at the DME under the drivers seat.