have a 91 RS. Tach was dead (needle stays all the way left, doesn't move), so i bought an z28 instrument cluster with 145 speedo from Hawks and installed it. Tach is still dead and I am almost 100% confident that the tach in this cluster was good. I need help with further trouble shooting.

I found the connector on the back of the distributor that goes to the tach and I pulled it, blew compressed air in it and reseated it. tach still dead

What is the next step to troubleshoot it? Thanks

 

Next step would be to find out whether you are getting tachometer pulses to the white wire in the cluster (pin #7 on connector C1).
That will tell you whether the tachometer is bad or the wiring needs attention.

Hope this helps.
Lou

 

Thats good info. Which connector is C1? I assume it is the one on the right as you look at the dash, that is, the on on the right side of the cluster, behind the tach? And where do I start counting to determine pin #7? top or bottom? Left or Right?

So to test it, should I just put one meter lead on the pin and one to ground? What am I looking for, voltage? Thanks

 

You're looking for a 12V pulsed signal, something like 5% duty cycle. It would be hard without a scope. Or if you have access to a function generator, you can try that instead and generate a pulsed signal on the white wire behind the tach.

Lou

 

Wow, thats great stuff. Mostly over my head, but some guys at work might be able to help me.

So those schematics represent the male connectors in the dash that you seat the cluster onto, right? Thanks again.

 

Looking at the diagram, the view is from the BACK, i.e. as if you're looking at the cluster when it's removed from the dash. Note the "passenger side" and "driver side" designation under C1 and C2.

Lou

 

You're right. I didn't look closely enough the first time.

So if I put a multi-meter set to Volts AC across the tach pin and the ground pin, that should at least tell me if I'm getting anything, right, even though I won't be able to tell as much as on a scope?

This is the second tach I've tried so I suspect I'm not getting anything to the tach.

It's raining here so i'll have to wait until tommorrow to try it. Thanks

 

P.S. This is the first time I've ever messed with electronics so I'm pretty clueless aout how to test things and such.