Gauges & their grounding

[k20]

Noticed a weird problem today sitting in the parking lot at school. I had the headlights on after I turned the ignition off, and the temp gauge spiked. Not just to H, but to like 4 oclock position. Restarted the truck, and noticed if you turn on the headlights, radio, cb, with each new electrical draw, the temp gauge moves ever so slightly.

How does that gauge ground? Is it grounded through the sender, or what?

Also, had a little annoyance with my voltmeter, it seems to like to dip down around 10 or so when Im cruising at a constant speed. Sometimes it will stay at 10 after I stop etc, checked the voltage and its a nice healthy 13.5-14.5 when the gauge is saying 10. Then when the gauge gets its act back together, it goes back to a tick above 13....

Is the voltmeter grounded somewhere? Dont really know how that gauge works, so dont even really know where to begin with that.

Last one is the oil pressure gauge. Normally at hot idle it sits at 45, and anything above idle will spike it. Sometimes however, it will sit at 30 at hot idle, just until I blip the gas, then it spikes and goes to its normal position.

Again, grounding? Does this sound like an insufficient ground from the motor to the frame/body, or is it some instrument cluster grounding?

I have no clue where the ground for the instrument cluster is...

Long post I know, but I despise anything with wires.

 

[dyeager535]

Instrument cluster itself is grounded through the Instrument Panel (IP) connector. Once you get the cluster out, you'll see the ground path on the PCB, and you can just trace that to the ground wire(s) on the IP.

With the volt gauge in particular reading incorrectly,and the other oddities I'd expect it's a connector issue.

One thing though, where did you measure voltage? Fuse panel or battery? Make sure to double check voltage at the fuse panel when this is happening. Very unlikely it's correct given the other issues, but it COULD be, if you didn't check from the fuse panel, which is where the gauges get their voltage from.