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Tachometer issue, any suggestions

1092 Views 4 Replies 2 Participants Last post by  Greg.
Just joined the site finally after reading many threads over the past couple years for helpful tips
Now,. Bought a '97 Ws6 with a few issues.
When i start the car the tach will read about 4000.
Then go from there under acceleration. The car idels fine.
What would make the gage read over 3000 off?
All factory gages. Everything else works fine,just the tach is out of wak.
I'd appreciate any suggestions.
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I would put your car on an obd2 scanner that reads real time sensor data. See if scanner reading matches or differs from what the tach reads. If the reading is different, then circuit card in tach is probably bad. But check your wiring from pcm to tach just to be sure.

Ah you say you don't have a wiring diagram. 96 factory service manual is available for download in 4th gen section. It shares about 99% of info with your 97.

Or if you insist on 97 wiring diagrams, get them at BBB Industries- Premium Alternators, Starters, Power Steering Products
I borrowed a scanner from AutoZone and no codes. I've never used the obd2. I try and access one thou. The car is fairly unmolested but has a few mods so a previous owner may have disturbed some factory wiring. How do i get to the tach card?
trouble with parts stores is they usually use a low end scanner that only reads codes.

You will have to get a more advanced scanner that also does real time sensor scanning. When you hook it up, it will give you the choice to either read codes or read running sensor data. The rpm count is one of the categories that should be displayed.

You will have to remove the instrument cluster and the tach to get to the circuit board. But there is no use doing so as the circuit board is not supplied as a spare to normal people.

Only companies that rebuild instruments have access to the part. And just try to get one from them. Been there done that, came back empty handed.

Your best bet is a good used cluster, or a good tach from a cluster. Be advised that different years use different styles of instruments, so try for the same year as you have.
Sound about right. My '04 Silverado gages are all shot. I'll look into another gage or cluster. Thanks for theinfo .
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