Hello my name is Dave.
It sounds to me like you have a ground issue somewhere in your instrument panel or in the wiring going to it. Most gauges work on a variable ground and if you ground the signal to them they max out. I have attached our tutorial on testing wiring. https://www.2carpros.com/articles/how-to-check-wiring
I would also like to provide you with the wiring diagram however the vehicle you listed is a 1983 Tahoe and they didn't make a Tahoe in 1983 therefore I can't feel confident I would be giving you the right diagram. If you could update the year/model we can provide you with the diagram and further guidance in tracking down the issue. Thank you for using 2CarPros and hope to hear from you soon with an update.
Thursday, April 4th, 2019 AT 4:33 AM