PontiacBonnevilleClub.com

Don't know if this is mechanical or electric -

Every now and then tach rpm needle briefly bounces up and down on its own (no change in engine rpm) and then resumes normal rpm indication.

Recently had harmonic balancer, Crank Sensor, tensioner assembly & serpentine belt replaced...

Any ideas?

Thanks

Check the connection to the ICM and crank sensor.

Also, the crank sensor is adjustable on these. Make sure the sensor is not hitting the rings on the back of the HB.

Thanks very much for the info - I'll have that checked out -

I know this year car has gauge issues too -

I'll let you guys know if anything is found... otherwise runs great...

I don't know why I like this car so much - costing me a few $$ 289,000 miles

Thanks again

TP

Not fast or real powerful, but they are comfortable. Same reason why I loved mine.

You have a number of connection points to get the tach signal from the module all the way back to the dash. The ones in the harshest environments are up in the engine bay, right at the connector going into the ignition module, plus another harness connector right about where the alternator is located. After that is the firewall body connector which is pretty well protected, and the rest are under the dash leading up to the big plug in the back of the instrument panel. For it to drop out then come back on it's own you may have a wire chafe grounding out the signal or a corroded contact in the weatherpak connections. (It's just the tach dropping out right?, the other gauges are working normally when the tach goes briefly nuts?)

I got the entire cluster for sale if you need it.
http://www.pontiacbonnevilleclub.com/fo ... 30803.html
PM me.

Thanks for all the add'l info

Well, may have figured it out - all other gauges working normally...

from the mechanic:

We replaced the TEVES brake unit with a used one from a Pontiac Bonneville Club member - seems that sometimes when using the brakes a some sort of weird short(?) occurs to make the tach needle jump about - it doesn't happen very often - I was just worried that the car would stall in the middle of the Long Island Expressway... he says not to worry - sooooo, I'll live with it - - - - when I have a few more $$ - I'll have him check the connectors etc mentioned by clm2112 - after all the car is 24 years old.... btw 292,000 miles....

Thanks again - TP

awesome heard the SSE lasts longer

Yeah - this is definitely a survivor - (don't want to jinx it) - but still runs like a tiger....

Only mod: put an '89 grille in with the double bars - didn't like the single bar.... replaced some badges that have fallen off etc.

Everyone here on the site is really helpful and good people!