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Hey all. I’ve been searching all over the interweb machine and found lots of similar things, but not specific to the issues I’m having.
98 Z28 Camaro, 5.7 with the six speed. I noticed while driving a few weeks back that it seemed like I was getting into redline range very quickly, but didn’t sound like it was that high. I was driving yesterday and the tach was pegged at seven grand doing 80mph in 6th gear. Motor was definitely not at 7,000 rpm. When I stopped at a stop sign when idling the tach was showing 3,000 rpm, but engine was definitely idling at normal range.
So…anyone experience anything like this? Thanks in advance!
Gauge cluster connnected by one large plug connector on the backside of the cluster. I'd check that connection and make sure it's clean. You could have a problem with the gauge cluster itself, the signal wire in the plug connector from the body control module to the gauge cluster or the tach wire to the ECM has become damaged causing a short.
Ok. So probably my first course of action should be hooking up my scan tool and seeing what the ECM is showing…which I kinda knew but was wondering if there was a common problem that plagues these. Guess I should have known if I can’t find anything on this specific issue that it must not be that common. If that reads good off the computer then probably the connection or the cluster I’d wager. I feel like if something was shorting I’d have blown fuses….but that’s not always true. Thanks for the input!
Originally Posted by 01CamaroSSTx
You could have a problem with the gauge cluster itself, the signal wire in the plug connector from the body control module to the gauge cluster or the tach wire to the ECM has become damaged causing a short.
IF you have had the car a long time then you can skip this step. Maybe someone has had the needles off?
Hook up scan tool compare RPMS at several different points and see how much of difference you are seeing between the scanner and the cluster ususlly theres 100-200 rpm variation. It's a direct connection from the ECM to the cluster no other modules are involved. I
'd be willing to bet the electronics in the cluster are at fault pretty common for gm tach clusters when they get old. You can take it to a dealer they can send it in to delco electronics to rebuild your stocker or by now theres probably internet companies out there doing the same.
I’ve had the car since August of 2018, rebuilt the motor and other things (it was hurt when I bought it) and it was always close to where it should have been. This is a new thing where it’s just way off.
I went out and started it when I got home
from work today and hooked up the scan tool. When started it read close to 4K rpm and settled down to about 3k after a few minutes. Computer is showing 730ish at idle. Definitely looks like a cluster issue….I think.
So, I bought a used cluster from a local guy. Came out of a 98 trans am. Everything works great again! Figured I’d post my fix if anyone else comes across this post in the future. Thanks for the input all!
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Tach reading wrong 
