290 square trim gauge issue

[Rscottdds]

I have an older style square trim gauge that’s having issues. It will say -4 when it’s all the way down for a bit like it’s supposed to but then just start showing random numbers. I changed out the potentiometer to a new one but it didn’t change anything. I had an issue a few years ago where the gauge wouldn’t change at all (stuck at 65 or something) so I got a replacement and it worked up until recently. Is the gauge bad again? Is there a way to troubleshoot? Those gauges are hard to come by and expensive so I don’t want to get one without being fairly certain it will fix the problem. Thanks for any help.

Robert

 

[Rscottdds]

All this is in the driveway with the key on but engine not running if that makes a difference.

Robert

 

[makomark]

most issues with instruments fall into three areas: 1)Power supply, 2) interconnects to sender, & 3) gauge internal issues (usually corrosion).

you can eliminate the first two by removing the gauge. hook it up on the bench with a power supply (fully charged battery) and a variable resistor.

The last area usually requires replacing the gauge...there are several internet vendors that specialize in refurbishing 'classic car instrumentation' - it may be worth making a few inquiries to find a viable source of repair...

 

[Rscottdds]

Thanks for the response. I don’t think it’s the potentiometer since I have a new one and things act the same. It could be the wiring as I just did a repower and they ran a new wiring harness but it was acting up a bit before that, just not as bad. The gauge is in an enclosed pilothouse so is pretty corrosion safe but the other one went out so idk. Do you know a place that fixes them? I’m guessing it’s probably going to be more expensive than buying a used one so where. I looked at it and it’s a fairly complex little gauge, at least it looks like it to me.

Robert

most issues with instruments fall into three areas: 1)Power supply, 2) interconnects to sender, & 3) gauge internal issues (usually corrosion).

you can eliminate the first two by removing the gauge. hook it up on the bench with a power supply (fully charged battery) and a variable resistor.

The last area usually requires replacing the gauge...there are several internet vendors that specialize in refurbishing 'classic car instrumentation' - it may be worth making a few inquiries to find a viable source of repair...