Tach and speedometer needles don't move, Can this be an ECU issue?
 

I have an 94 FD3 and my blinker didn't work for the past 12 months. I finally bit the bullet and took it into a mazda dealer. After 3 days the tech found a bad connector and fixed it. I drove home and everything was fine. I started the car 30 minutes later and my tachometer and speedometer needles wouldn't move.

I took the car back to Mazda and after 3 more days the tech said it was the speedometer computer in the ECU.

I just purchased an ECU off of Ebay and installed and my tach and speedometer still don't work (needles don't move at all).

I assume that they're not both broken and that the ECU wasn't really the problem.

Any suggestions?


Also, I had an Automatic ECU but did a tranny swap to a manual 2 years ago. I purchased a manual ECU for the same year, but now my air bag light blinks, then goes out for a few seconds, then blinks again. Any help would be appreciated!

the ecu does provide the tach input, but that is all it does. the speedo is driven right from the transmission, so therefore if both don't work, its likely to be a power or ground issue.

the airbag also has a separate controller box, so the engine ecu has nothing to do with the airbag system