Volt Gauge 1985 Silverado

[GRADYS Performance]

Does anyone have experience repairing a 1985 Silverado in dash voltmeter? All the other gauges read fine but the voltmeter does not read at all. Is it part of a circuit board or are the gauges individual?

[Keith Seymore]

Originally Posted by GRADYS Performance

Does anyone have experience repairing a 1985 Silverado in dash voltmeter? All the other gauges read fine but the voltmeter does not read at all. Is it part of a circuit board or are the gauges individual?

It goes through the printed circuit board, as do the other gages.

K

[GRADYS Performance]

Any way to repair it or do I have to replace the completer circuit board?

[ray_mcavoy]

The printed circuits themselves are generally quite reliable. Problems usually tend to occur at the connection points and can often be repaired with a bit of cleaning.

In particular, look at the little metal clips that connect the printed circuit to the studs on the back of the gauge. Look for rust on the clips and/or corrosion on the printed circuit's copper where the clips make contact. If necessary, carefully snap the clips out of the holes, clean up the contact points, and snap them back in. To prevent future corrosion between the two metals, I like to use a little bit of conductive anti-oxidant compound (available in the electrical section of most hardware stores).

Also take a look at the cluster plug connection points. Look for damaged traces on the printed circuit where the plug's terminals make contact. Also look for bent or deformed terminals in the cluster plug that could be preventing a good connection.

Finally, there is a current limiting resistor on the back of the voltmeter itself. It's held in place by a couple of nuts. Make sure those nuts are secure (but not too tight or it'll crack the ceramic resistor substrate). It's rare, but those resistors can fail and cause the voltmeter to quit working. You can test it with a multimeter ... I think that resistor is close to 130Ω on most of these voltmeters.

[Dead Parrot]

Here is a voltmeter. Not sure what year it is from but is likely similar to what you have.
Attached pics of front, back and connected to a 12V source. The blue thing on the back is the resistor. This one measured out at 125 ohms. Note that this one is reading 13V with a 12V input. If you don't have an adjustable power supply, you can use a 9V battery. Green = ground, red = positive.

[Keith Seymore]

Originally Posted by ray_mcavoy

The printed circuits themselves are generally quite reliable. Problems usually tend to occur at the connection points and can often be repaired with a bit of cleaning.

In particular, look at the little metal clips that connect the printed circuit to the studs on the back of the gauge. Look for rust on the clips and/or corrosion on the printed circuit's copper where the clips make contact. If necessary, carefully snap the clips out of the holes, clean up the contact points, and snap them back in. To prevent future corrosion between the two metals, I like to use a little bit of conductive anti-oxidant compound (available in the electrical section of most hardware stores).

Also take a look at the cluster plug connection points. Look for damaged traces on the printed circuit where the plug's terminals make contact. Also look for bent or deformed terminals in the cluster plug that could be preventing a good connection.

Finally, there is a current limiting resistor on the back of the voltmeter itself. It's held in place by a couple of nuts. Make sure those nuts are secure (but not too tight or it'll crack the ceramic resistor substrate). It's rare, but those resistors can fail and cause the voltmeter to quit working. You can test it with a multimeter ... I think that resistor is close to 130Ω on most of these voltmeters.

Excellent post; thank you, Ray (I'm not very good with electrical diagnosis and repair).

Originally Posted by GRADYS Performance

Any way to repair it or do I have to replace the completer circuit board?

They may be available and (relatively) inexpensive so replacement might be the best option.

I have repaired obvious breaks in the printed circuit using a repair kit designed for rear window defogger grids, and have also reworked printed circuits by adding a small separate jumper wire.

K

[motornut]

I used crazy glue to reattach the paths that lift
the plug seem to move some loose at times
a light sanding,and a little pry up on the contacts helps too