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Help! tach inaccurate?

Joined
Mar 17, 2014
Messages
11
Location
clearwater, fl
Corvette
1990 hatchback dark red
I think the tach on my 1990 L-98 reads too high, it will rev way beyond the red line, speedometer is still climbing. I have never kept accelerating until the "rev limiter" engages.

My question, is there an adjustment, or where should I look to correct the problem?

It idles at indicated 1400 rpm, I connected a tune-up tach to the distributer and it reads 675rpm at idle.

Help!!

thanks

George
 

GWinter

Well-known member
Joined
Oct 2, 2005
Messages
52
Location
NW Iowa
Corvette
1990 conv. 6sp
GM tachs in Camero and Corvette around that time period are known to go bad. There are youtubes on how to repair them . If you can't repair it you need to remove the cluster and replace it or have it repaired. My 90 does the same thing , just haven't found the time to take care of it .
 

DonB

Well-known member
Joined
Mar 25, 2015
Messages
339
Location
Chicago
Corvette
2019 ZO6 in Elkhart Lake Blue
There is a resistor in the tach IC that goes bad. I've had to do the repair and it works like a charm. You will need to take the circuit board out of the dash and solder in resistor(s) of a specific value in a specific location. I had a local TV repairman I know do the board repair on mine once I pulled the board out. It entails some precise soldering.

Check out the previous posts or look on Utube as mentioned.

This is a very common problem.

Good Luck.
 
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