Cluster Gauges Pinning

[67 GTX]

The other day, out of no where my temperature and gas gauge, in my 67 GTX pinned full right after start up. They eventually went back down, but they definitely pinned.

Does this sound like a bad voltage regulator on the cluster itself, or just a loose one?

 

[FrnkNsteen]

I don't have enough experience with the voltage limiters to say if they can intermittently go bad and cause high voltage to the gauges, but I would definitely look at that. Other causes could be losing resistance to the gauges (like the wires are going straight to ground) but I would think it would be unlikely that both wires would be getting full ground. That would lead me to look for the common cause, and too high of voltage can cause them to peg out like that.

Not much to those gauges. They need 5 volts and resistance somewhere between 75ohms on the low side and 10ohms on the high side. Too high of voltage, or too low of resistance will cause them to peg out and could burn them up.

 

[PlainfieldCharger]

The original voltage limiter that is on the cluster gauge circuit board is mechanical and could have stuck for a moment in the closed position. I would replace that with a newer electronic one. I put IV4 Solid State Instrument voltage limiter push in type. no problems since..

 

[67 GTX]

The original voltage limiter that is on the cluster gauge circuit board is mechanical and could have stuck for a moment in the closed position. I would replace that with a newer electronic one. I put IV4 Solid State Instrument voltage limiter push in type. no problems since..

That's something I can look into. Where did you get the new instrument voltage regulator from?

 

[PlainfieldCharger]

I got if off ebay....

https://www.ebay.com/itm/Solid-State-Mopar-Limiter-IVR4-push-in-B-body-A-body-others-/380917322935
This is it...

 

[67 GTX]

Do you guys know of a way to test the cluster voltage regulator? To make sure it's dropping the 12 volts to 6?

 

[67 GTX]

I replaced the instrument voltage regulator, and everything worked fine for the first few times I ran the car.

Now last time I started the car, when it was already warmed up, both the temp and gas gauge pinned, before going back down and finding their correct reading.

This doesn't seem normal, especially since this is what broke my last temp gauge.

 

[FrnkNsteen]

Where did you get the new instrument voltage regulator from?

I got mine from Real Time Engineering (link below), but mine is for the 68-70 rally dash. You could contact them and see what they offer for your car.
https://www.rt-eng.com/

 

[Mike 71X]

So I have a similar but slightly different problem. Gauges maxed permanently so changed out the voltage limiter for a new solid state one. This worked for a few days but now the gauges are opposite, they barely come up at all. Could it be the new solid state limiter has gone bad also and failed the other way. (Will be under the dash shortly checking the output voltage per the recommendations above). Or could it be since they were pegged before they are all now burned out? We pulled another voltage limiter out of a parts car and get the same results, needles barely come up. Nothing to say that limiter isn't also bad.

 

[PlainfieldCharger]

I would check the circuit board in the area where the voltage limiter inserts. Check if for damaged solder joints or damage on the board. If you find nothing there it sounds to me that the ground to the dash cluster is lacking. Also check the ground to the whole dash assembly...

 

[Mike 71X]

We were able to verify the limiter was providing 5 volts to the gauges which is the spec. It appeared the oil pressure gauge was working and verified this with a mechanical gauge. So this meant it was only the temp and fuel gauges. An article on Allpar said the fuel sending unit should measure 8-10 ohms when the tank is full, that checked out so it appears the two qauges in question have issues. I read somewhere that all 3 of these gauges use the same resistance scale so we tried swapping the wires. When we put the fuel wire to the oil pressure gauge the needle shows "full". Connecting the temp wire to the oil pressure gauge gives a needle position just under half which is where the temp gauge was before all this happened. Conversely putting the oil sending wire to the other gauges showed virtually no reading. So thinking these two must have gotten messed up when the original limiter pegged them out. They still move a little so hoping can just send them off to be recalibrated.

 

[67 GTX]

What's weird with me is that if the car is hot and I turn it off, then turn it on again after a few minutes, the gauges pin, then go back and read correctly.

The temp gauge seems to pin a bit harder, so I disconnected the water temp sensor on the water pump housing. Anyone had that sensor start acting wonky?

 

[Fran Blacker]

Had one where the gauges would go toward pinning the gauge. Then a ping and gauges would go down to normal then start rising then ping. back toward normal.

 

[Mike 71X]

Had one where the gauges would go toward pinning the gauge. Then a ping an gauges would go down to normal then start rising then ping. back toward normal.

I've read that sometimes you can hear the old voltage limiters cycling.

 

[67 GTX]

I just replaced the regulator to be on the safe side, but the issue persists

 

[threewood]

So I have a similar but slightly different problem. Gauges maxed permanently so changed out the voltage limiter for a new solid state one. This worked for a few days but now the gauges are opposite, they barely come up at all. Could it be the new solid state limiter has gone bad also and failed the other way. (Will be under the dash shortly checking the output voltage per the recommendations above). Or could it be since they were pegged before they are all now burned out? We pulled another voltage limiter out of a parts car and get the same results, needles barely come up. Nothing to say that limiter isn't also bad.

If they were maxed out for too long the gauges may have been hurt. 12v puts way too much heat through the bi-metal contacts inside the gauges and will permanently warp them.

An easy way to test the new IVR is to turn ignition on and ground the sending wire for a sec or two. Have someone watch the gauge needle, it should move all the way right but don't pin it.

Or with ignition off supply the positive gauge stud with 5v from a battery and see if it shows normal.

 

[67 GTX]

What would be causing the gauges to pin? Especially since the IVR was replaced?

 

[67 GTX]

The issue now seems to only occur when using my headlights switch. When I turn the headlights on, if I turn the switch to give my cluster full brightness, I can watch the water and gas gauge go towards high until they'll ultimately pin unless I turn the brightness down.

The headlight switch is a new one. Any idea what's causing this?