Dash problem on 1990 K1500

[Free88]

I just purchased a 1990 Chevy K1500 4x4. The problem is the oil gauge buries itself all the way to the right and the volt gauge goes to the right all the way.
I tested the battery and it was putting 12.7 to 13 volts depending on load. Alternator was putting out 14 volts when I tested it.
The volt gauge also flicks back and forth when you use the signal. Could this be faulty gauges or a bad ground?

Thanks for the help.

[ChevyTech]

It does sound like a ground problem, but also consider the possibility of two problems.

It is very common for the oil sending units to fail on these trucks and if you unplug the oil sending unit the gauge will go all the way to the high pressure end.

These dash panels do have issues with losing connection where the connector plugs on the back.

I have looked up the ground path for these trucks in the past but nobody has ever pursued and repaired the turn signal making the volt gauge swing and gotten back to me about it. If I remember correctly the instrument panel ground wire connects to the chassis right next to the ALDL connector.

[Free88]

Thank you. I have changed the circuit boards on he rear lights and the problem still exists. I will have to look under the hood and see if the oil gauge has been disconnected. Could I run a separate ground from the taillight to the chassis at the back to improve grounding. Front park lights are bright and seems to working, they do not dim or anything when the signal is put on.

[ChevyTech]

Originally Posted by Free88

Thank you. I have changed the circuit boards on he rear lights and the problem still exists. I will have to look under the hood and see if the oil gauge has been disconnected. Could I run a separate ground from the taillight to the chassis at the back to improve grounding. Front park lights are bright and seems to working, they do not dim or anything when the signal is put on.

I think the problem that is causing the volt gauge swinging with the turns signal is not back by the tail lights or in front by the turn signals.

Your truck is not the only one with this problem.

I have never actually got to trace down the problem on one of the trucks doing this, but it is my opinion that the problem is in the instrument panel itself, the connector to the instrument panel, or the ground wire to it. This is just my educated guess. I have read several posts on the message boards about this and nobody has posted a repair for it.

[JohnO356]

On my '88 C1500 the volt gauge moves down just a little with the turn signal flash. I've always just considered this "normal". It's occurred on several different vehicles I've owned.

[ChevyTech]

On my '88 C1500 the volt gauge moves down just a little with the turn signal flash. I've always just considered this "normal". It's occurred on several different vehicles I've owned.

Some volt meter movement with the turn signals flashing, I would consider normal and would not worry about.

…and the volt gauge goes to the right all the way.

If the volt meter is going all the way to the right or swings all the way off the end of the scale, it is not normal.