I was driving this morning to work and my tach suddenly dropped dead! I stop and restarted the car and nothing happened, any help please, thanks

 

I had something similar happen in my zx2 and my alternator died shortly after (like 15 minutes of driving wise). Not sure if this is the same with the RX7's, but it's a thought.

 

Check your trailing coils per the FSM. I believe the TACH gets its signal from there. It is very easy to check the coils, you just use a DMM to check the resistance across the posts.

Aslo check for continuity between the coil and the negative side of the battery (make sure it has a good ground in other words).

 

check the fuses in your engine bay

 

well 1 year later,it happened again,ive check the coils near the firewall and everything seems to be connected.im i checking the wrong coil pack? Thanks for the help in advance

 

anyone wanna take a poke at it?

 

I had a similar tach problem.

At first it just died, then intermitantly it would decide to work, but it was wrong...like if I should be at 7k it was reading 3.5k.

Turns out it was the grounds up under the coil near the clutch master cylinder. After I took a lil sand paper and dielectric grease to them it was good as new.

 

Tach signal does indeed come off of the trailing coil. If the coil is not running, the tach will read zero. Sometimes this is corrected by simply restarting the car. If not, take the advice of others here and check the ground under the trailing coil, and check the coil itself. I have a little $2 spark checker that I insert in-line between the coil and the high-tension lead; it lights up if there is spark. It is a quick and painless way to check to see that the trailing coil is operating. If it is, it may be a problem in the wiring between the trailing coil and the tach.

The trailing coil is the one in the left rear of the engine compartment, just aft of the left wheel well.