Well I searched for "tach" and didnt come across anything that had my symptoms. So here it goes
I recently received my car back after I had a coolant hose leak and a welding job done on my rad. But after I got it back and drove it around my tach decided to start acting up. It will not go above 1k but it reads while idling and anything under 1k. I have a pfc and that hasnt been touched so I highly doubt its that. But everyone says it could be my coil or loose sensor cable or a loose connection on the tach gauge. Im sure the gauge is not bad b/c it still does read something but my pfc is reading normal rpm ranges. Any help is appreciated. Also anyone know where I can find the sensor to the tach and the coil. Btw like I said it wont hit 0rpm it always on just reads only 1k and doesnt seem to want to go past.

 

Bump

 

Anyone ??????

 

31 views and no response. Cmon...

 

See the Body Electric section of the Factory Service Manual.

The tach generally either works or it doesn't. If it doesn't have signal, it's dead.
If it does have proper signal, it should work, if not, the signal is spotty or it is replacement time because as far as Mazda is concerned, they aren't serviceable. IIRC, it gets signal from the ECU via the CAS (which you kinda-need for the car to even run). Also you could hook up an aftermarket tach to the diagnostic pin and see if it reads okay.

I hope they welded the radiator outside of the car.
Welding on a car with the ECU connected has been known to damage it.

Sounds like you need to pull the gauge cluster out and have a look-see.

 

Thanks for the reply . Ya they took the radiator out b4 welding it . I checked ecu connections and they were on correctly. I also looked around the engine for loose connections. Non to be found as of yet. But like I said the person who tuned my car was watching the pfc and it was reading correctly and when he was putting on the old o2 sensor he must have tapped something which i cant seem to fine and it started working again. Soooo I am currently looking at the manual to find this wire. Thanks again for your reply.