Tachometer

[JimBobTX]

I have just purchased a 1990 ZR1 with about 26,000 miles and the tach is not working correctly. At high revs it only shows about 2200 but it slows down to about 700 at idle. Does anyone have any suggestions about what might be the problem?
Thanks

[DRM500RUBYZR-1]

The tach needs to be removed and sent out for re-calibration.
Common problem.
Once removed, repair is under $150.00
I send them here:
https://www.ebay.com/itm/TACHOMETER-REPAIR-SERVICE-90-96-C4-Analog-Corvette-Tach/142558243932?hash=item2131222c5c:g:cDwAAOSw9gRZ92E 7

Marty

[JimBobTX]

Marty,
Thanks, I have looked on youtube for a tutorial on removal of the dash cluster but could not find one. Do you know of a source of information on this removal. I could just start taking screws out, but would prefer to start the job with some knowledge that I was doing it right.
Thanks

[Paul Workman]

Very likely, the calibration issue is due to a printed resistor (chip) board which is available from BANTEE.com. OR, you can send the entire cluster to them and have replace it for you for ~ $150 plus shipping - with the advantage of having them go through the entire cluster and check it out!

Removing the cluster isn't hard at all, and it isn't a bad DIY project for anyone mechanically competent and who can solder on a PC board.

As for how to remove the cluster, do a SEARCH on tach calibration. The article goes through the "how to" remove it. And too, it goes into detail on how to select and install the discrete resistors to return the proper voltage for calibrating the tach.

[-=Jeff=-]

to remove the Cluster (Going off of memory):

- remove the left side trim (3 screws) this trim has the hood release symbol on it
- Remove driver side hush panel (4 screws are hidden in carpet ( might be some underneath, there is also a ring type clip near the accelerator pedal
- Remove OBD connector (7mm)
- Remove metal lower plate seen once carpeted hush panel is removed (4 bolts)
- Remove cluster bezel (it will not come out until column is dropped)
- remove 2 bolts and drop column (you might need to remove tilt lever)
- unbolt cluster and remove

[Ccmano]

http://www.batee.com/corvette/dcrg/services/9096_repair.html
H

[Paul Workman]

I found this article I did for HOTB in 2012. It describes the procedure for removing the cluster and identifies the resistor voltage divider (chip) which is 99% of the calibration issues.

You can now purchase a replacement chip from BANTEE, (IIRC), which perhaps would relieve you from the process of determining the resistance needed to calibrate the tach.

Anywayz...this (below) may be of some use still...

.

[JimBobTX]

Paul,
Thanks, This looks to be very helpful. I will be working on it after Memorial day.
Thanks again
Jim

[jmglyder]

Hello,

I used these steps from Bantee.com to remove my cluster and it went very smoothly.

Removing Your Instrument Panel

-Remove the negative battery cable! This prevents codes from being set when we
remove the instrument panel.
-Tilt the column to the lowest position.
-Unscrew the tilt rod and remove it.
-Remove the carpeted plastic trim piece below the steering wheel.
-Remove the steel plate revealed by step 4.
-Remove the two bolts that hold the "Y" shaped plate and the steering column in
place.
-Let the steering column drop.
-Remove the trim piece around the instrument panel. It's just a few phillips
screws.
-Remove the four screws which hold the instrument panel in place. They're
usually 9/32".
-Pull the instrument panel straight out.

[Paul Workman]

Hello,

I used these steps from Bantee.com to remove my cluster and it went very smoothly.

Removing Your Instrument Panel

-Remove the negative battery cable! This prevents codes from being set when we
remove the instrument panel.
-Tilt the column to the lowest position.
-Unscrew the tilt rod and remove it.
-Remove the carpeted plastic trim piece below the steering wheel.
-Remove the steel plate revealed by step 4.
-Remove the two bolts that hold the "Y" shaped plate and the steering column in
place.
-Let the steering column drop.
-Remove the trim piece around the instrument panel. It's just a few phillips
screws.
-Remove the four screws which hold the instrument panel in place. They're
usually 9/32".
-Pull the instrument panel straight out.

Yes, and OP while you have the cluster OUT, that is a dandy time to clean off any oxidation "frost" on that large connector at the left corner of the cluster, and too the male side in the dash as well. With a little brush, I put a thin coating of dielectric grease on the connector (male and female sides). I've NEVER had an issue with (the usual flickering, intermittentcy, etc.) since these many years since...just sayin!