[CAPNAL2001]

My 2001 sierra 2500 hd has a couple of electrical issues: One, the tachometer only works when the brake pedal is pressed, leading me to think a bad ground is the culprit. Two, the fuel gauge is intermittent, and also SOMETIMES changes when the brake pedal is pressed. Do you guys have a suggestion on where I should look FIRST? I don't want to go through the entire system if somebody else has had luck with checking the _______? Thanks for any help

 

[GMT604]

Probably not a ground issue, the tach shares the ground with the rest of the cluster so you would have more cluster problems. The tach is wired direct to the PCM from Pin A2 of the cluster, white wire. Any aftermarket electronics, like a remote start? If so I would be looking there, a remote start would require a tach signal and also a brake signal.

The fuel gauge acting up is common, sulfur buildup and corrosion on the sending unit. Try a bottle of Techron to 1/2 tank of fuel and see if it improves.

 

[GR2017]

I see "bad ground" mentions in many forums. I have owned various vehicles for over 50 years (including British, German and USA) and have never once had an issue that was related to a "bad ground".