I have an 86 car with voltmeter that pegs to 16+.

Does this mean that the circuit resistor is bad? Has anybody here ever done surgery to fix one? Am not talking about the 68ohm on back of ribbonhat manages the alternator excitement.

Am speaking of the one wired to the back of what is apparently the gage circuit.

I have gage's removed from 84 and 86 panels.
tested each on battery side by side. 84 read 12 volts, and I could wind it up a few volts by turning the pot with screwdriver. 86 gage pegged, just like it always has in the car. Pot adjustment doesnt change it, pegs regardless. So clearly it's a gage problem. I see a resistor on each. I guess I'll measure across it next and compare.

I'd just swap, but they look too different in configuration, 84 wont fit into 86 panel I dont think.

Any thoughts on this one?


1984 voltmeter.

86 voltmeter. Resistor grey, pot above to right.


I know virtually nothing about to execute a clean tech fix in electronics.. Assuming the grey resistor is bad, do I clip it out and swap for 84, which is surplus?

Is there some sort of crimp that could be used to bond the cut leads on 86 to the 84 resistor leads? Seems there is enough heavy gauge wire protruding to do that.

Or do I have to disassemble more and solder directly to whatever board is on the backside?

 

this seems to be a common problem. does the one that's pegging work ok for a couple minutes when it's cold? i had fits with mine for a while...it started acting up after i hard wired the cluster (ditched the mangled printed circuit board). the voltage readings were high at times, normal at times, and pegged one time....i shut the car off and the gauge remained pegged. so, i started wondering if i had a bad voltage regulator, and along with the additional transmission capacity of the hard wires, maybe it was heating up the gauge. then it just started working correctly. so i never could track down the issue. just curious....how are you testing the 84 gauge vs. the 86 gauge??? are you using the same ground for each test? bad ground can peg the needle...

 

Did you ever resolve this? The voltmeter on my 94 has been pegged (when running) since the day I got it in 96. The time I mentioned it to the dealer service manager he just said "That's normal". My interpretation at this point is that the service department didn't want to fix it. Anyway, since the voltage at the battery reads around 14V (when running) it's unlikely the meter is reading correctly. I'd be interested in your solution if this thread is not too old to be resurrected.

How much adjustment is available in the POT?

 

Yes, sort of.

The 86 pegged meter was indeed bad.
i confirmed it by temporarily swapping the whole gage pod of another 86.
I did not try to replace the subcomponents or send it off for repair. Should have, or should have sourced a correct replacement.

instead, set out to make the swap of 84 into 86. The pot had enough range. But the mounting configuration was totally different, resulting in making mods to the 86 plastic carrier. Really shaky repair. Looked ok, worked, but just plain wrong.

when I sold that car, muscat brown 86, I disclosed the repair and the buyer knew he should correct it.

if it is pegged, it’s bad. Source right one for your car. Trickiest thing when working on these gage sets for me is re-pressing the indicator needles back onto the gages. Possible to bend the gage shaft. My old hands and eyes made that part harder than I’d remembered it 10 years prior when repairing various 928 odometers.

regarding frequency of occurrence, I’d not heard of it before and couldn’t find references. Before repairing, I presented the problem to Howard in Atlanta when visiting during No.1 rendezvous. He adamantly suggested there must be another problem, and he’d never seen bad gauge. Weird case I guess.

its been a while, seems it did act intermittently a few times, but was usually pegged. I tried all kinds of wire tracing and contacts cleaning, battery and alternator swaps as I had spares. But none of that affected it. Had to be gauge itself. And it was.

 

Thanks for the update. I had a spare volt gauge at one time, but no longer. I'll let the thread float a bit and see if other options show up, but it would not surprise me the gauge is bad. Too bad I didn't insist on a repair way back in 1996, the replacement part would have probably been a lot easier to get at that time. Oh well. I have pulled that instrument cluster about 10 times, I don't like it because it is so stinking tight to get in and out, but, it won't be the first time!