Hey, what the heck is going on with my Charger gauges?

[cruiser]

Hi Guys/Gals:Cruiser here. Maybe you could offer your opinion about a strange gauge situation on my 1969 ChargerRT/SE. My car has been completely restored to stock, including all wiring. The dash instrument cluster was professionally rebuilt, and a new solid state voltage limiter was installed. Here's the weird part. Sometimes, the temperature and oil pressure gauges seem to read unusually high, for no apparent reason. One day, I'll be driving and the temperature is nailed right on 195 degrees (it has a 195 degree thermostat), and the oil pressure at highway speed is 55 psi. All normal. The next day under identical conditions, the same temp gauge will be reading 215, and the oil pressure is up to 65. After I stop and restart, the temp and oil pressure go back to normal (195 degrees and 55 psi). I have no reason to suspect that the temp was really 215, or that the oil pressure was actually 65 psi. It just temporarily reads that way. Every once in awhile, I'll observe the fuel, temp and oil gauges momentarily drive to nearly full right, stay there for a moment, then go back to normal. So what do you think the fault is? Like I said, all wiring and the circuit board seem good, and it has a new solid state voltage limiter on the back if the dash. Ideas? Thanks.

 

[pnora]

Hi Guys/Gals:Cruiser here. Maybe you could offer your opinion about a strange gauge situation on my 1969 ChargerRT/SE. My car has been completely restored to stock, including all wiring. The dash instrument cluster was professionally rebuilt, and a new solid state voltage limiter was installed. Here's the weird part. Sometimes, the temperature and oil pressure gauges seem to read unusually high, for no apparent reason. One day, I'll be driving and the temperature is nailed right on 195 degrees (it has a 195 degree thermostat), and the oil pressure at highway speed is 55 psi. All normal. The next day under identical conditions, the same temp gauge will be reading 215, and the oil pressure is up to 65. After I stop and restart, the temp and oil pressure go back to normal (195 degrees and 55 psi). I have no reason to suspect that the temp was really 215, or that the oil pressure was actually 65 psi. It just temporarily reads that way. Every once in awhile, I'll observe the fuel, temp and oil gauges momentarily drive to nearly full right, stay there for a moment, then go back to normal. So what do you think the fault is? Like I said, all wiring and the circuit board seem good, and it has a new solid state voltage limiter on the back if the dash. Ideas? Thanks.

What does the fuel gauge do? By rights if the limiter was acting up it should affect all 3 gauges.

 

[4mulas]

Check all grounds.

 

[cruiser]

What does the fuel gauge do? By rights if the limiter was acting up it should affect all 3 gauges.

Fuel gauge seems okay, except for that rare instance when all three gauges drive toward full right, then come back by themselves. Very weird.

 

[cruiser]

Check all grounds.

Yeah, checked them. All seem good.

 

[Demonic]

all three gauges drive toward full right

Your IVR is sticking, and spiking 12v to the gauges. If it stays that way, the gauges will fry. Swap to an electronic one from RTE.

https://www.rt-eng.com/

 

[Sixpactogo]

I had a similar issue with my 68 Charger. Gauges would act up and wander around some. Turns out the cluster was not getting a good ground. We all have a tendency to paint the dash panel when it is out and stripped bare. Paint is not a friend to good grounds. I scraped the paint off around the mounting screws and the problems went away. A good way to verify is to use your Ohm meter. Check between Neg on the battery and at the cluster. If you get .3 ohms or better, you have a good ground.

 

[pnora]

Fuel gauge seems okay, except for that rare instance when all three gauges drive toward full right, then come back by themselves. Very weird.

That is the instrument voltage regulator causing that. If you were to clip a volt meter on any of the gauge's input terminals you could monitor the voltage. You should see about 5 volts normally and when they act up you should see a higher voltage.

 

[cruiser]

Check all grounds.

If I wanted to eliminate a bad instrument cluster ground as a problem, I could create an extra ground wire to be absolutely sure the cluster was properly and completely grounded. Where would be a good place to hook into the instrument panel to run an extra ground to the body? Ideas?

 

[4mulas]

If I wanted to eliminate a bad instrument cluster ground as a problem, I could create an extra ground wire to be absolutely sure the cluster was properly and completely grounded. Where would be a good place to hook into the instrument panel to run an extra ground to the body? Ideas?

I suppose any where to the dash itself as the dash is grounded via it’s mounting points. Or even to the firewall etc.

Make sure the column ground wire is tight and grounded securely too. I did have one car that liked to put the gas gauge to full when the left signal was used.

These things can be frustrating, stick with it and just keep eliminating things ones by one and you’ll find it!

 

[hunt2elk]

If I wanted to eliminate a bad instrument cluster ground as a problem, I could create an extra ground wire to be absolutely sure the cluster was properly and completely grounded. Where would be a good place to hook into the instrument panel to run an extra ground to the body? Ideas?

I do that on all my cars just for extra insurance. I run a #10 from the battery - to the dash frame right of the ignition switch. Then a #14 from there to the instrument cluster. I use that point on the frame for other grounds as well. Radio, aftermarket gauges, misc.