Oil pressure gauge AND water temperature gauge not working

[Michael_]

Since i have the car sometimes the oil pressure gauge, sometimes the temperature gauge isn't working.
Right now both don't work. (Since about a month now)
Except the clock (needs probably rebuilt) and backlighting (probably the dimmer switch) all other gauges work just fine.

I already checked the fusebox and took out the relevant fuse, everything fine.
We already removed the bulkhead connectors and tested the connections under the hood, i'm not an electronics engineer but it seems fine.

So at this point i'm 99% sure the problem is on the cabin side, inside the dash.

Given 2 gauges make problems, right now both aren't working i assume it's probably not the gauges themself.
Is there a component in the circuit that could make especially the oil pressure and temperature gauge fail?

What could it be?
I will probably remove the gauge cluster / open the dash because i hate aftermarket underdash gauges.

Its a 1969 Dodge Charger R/T with the 440 and therefore rallye cluster.

 

[TopBanana72]

Could be the "voltage limiter". It is a small silver box attached to the back of the dash. Has a capacitor screwed to it. I had mine fail and it caused the temp and gas gauge to stop working. Not sure if it affects the oil gauge though.

 

[davek]

does your gauge cluster have all the mounting screws -5? ground the gauge cluster and see if that makes a difference before you pull everything.

 

[Demonic]

Does the gas gauge work? The insturment fuse is 3A.

 

[Michael_]

Could be the "voltage limiter". It is a small silver box attached to the back of the dash. Has a capacitor screwed to it. I had mine fail and it caused the temp and gas gauge to stop working. Not sure if it affects the oil gauge though.

Can this be replaced without opening the dash / gauge cluster?
Who makes a dependable replacement? It looks like i just had 3 bad fan clutches...

does your gauge cluster have all the mounting screws -5? ground the gauge cluster and see if that makes a difference before you pull everything.

What does "-5" mean? 5 Screws?
How do i best ground the gauge cluster? Can i check if the factory ground is in place without pulling it? If so where is it located?

Does the gas gauge work? The insturment fuse is 3A.

Yes the gas gauge works. Could the voltage limiter still be the issue?
I already checked the fuses, fuse box and it seems to be fine. There is also zero corrosion.
I can order some replacement fuses though and try before pulling it apart.

 

[Sixpactogo]

Since your gas gauge works, the voltage limiter is working. My guess your oil and temp gauge issue could be in loose connections at the pins on the back of your cluster. You are probably right by suspecting the dimmer switch as the problem for no dash lights. The cluster gets its ground through the mounting screws. I think you are stuck with pulling the cluster but it's not that hard. You will have to drop the steering column a little, remove the cluster and radio bezel screws. Unhook the speedo cable and you should be able to pull the cluster out enough to unhook the wiring harnesses. Once out you can bench test everything pretty easily. Be sure to check the connections at the pins for the gauges. Those connectors are pretty chinsy IMO.

 

[Billccm]

IVR is suspect. Doesn't hurt to upgrade this to the safer, more reliable rt-eng.com IVR.
That's the plug and play fix. Next it's probably time to look at circuit board pins and trace connection.

 

[pnora]

Hang on. The gas gauge works so it is not the voltage limiter. PERIOD. Simple test. Unplug the oil sender and hook a ground wire to the wire. Turn the key on the oil gauge should go to full. Then do the same to the temperature sender and it also should go to full. Perform those two simple 1 minute tests and report back.

 

[Michael_]

Simple test. Unplug the oil sender and hook a ground wire to the wire. Turn the key on the oil gauge should go to full. Then do the same to the temperature sender and it also should go to full. Perform those two simple 1 minute tests and report back.

We already did that with the temperature gauge and the gauge did not move.

IVR = Voltage limiter?

 

[Michael_]

How can i put a temporary ground on the cluster for testing?

 

[pnora]

We already did that with the temperature gauge and the gauge did not move.

IVR = Voltage limiter?

No not Limiter. Dont you read? Your gas gauge works that means the limiter is working.

 

[Michael_]

No not Limiter. Dont you read? Your gas gauge works that means the limiter is working.

What i mean't is what does IVR mean.

 

[Michael_]

Okay seems that IVR = Instrument Voltage Regulator and according to the posts it's not my problem.

Edit:
Is the Voltage Limiter and Regulator (IVR) the same thing?

 

[pnora]

Okay seems that IVR = Instrument Voltage Regulator and according to the posts it's not my problem.

Edit:
Is the Voltage Limiter and Regulator (IVR) the same thing?

yes

 

[Michael_]

ground the gauge cluster and see if that makes a difference before you pull everything.

How can i do that, anyone?
Or is all i can do check the 5 screws are there and tight?

 

[pnora]

We already did that with the temperature gauge and the gauge did not move.

IVR = Voltage limiter?

Did you try the oil pressure gauge?

 

[pnora]

How can i do that, anyone?
Or is all i can do check the 5 screws are there and tight?

The ground is good if the fuel gauge is working.

 

[Michael_]

Did you try the oil pressure gauge?

No, i can but i will have to pull it apart for the temperature gauge anyway.
It's the most important gauge for me.

The ground is good if the fuel gauge is working.

The same probably goes for the fuse(s)? (which i checked)

 

[pnora]

No, i can but i will have to pull it apart for the temperature gauge anyway.
It's the most important gauge for me.



The same probably goes for the fuse(s)? (which i checked)

Do it.

 

[Michael_]

Do it.

I will. As soon as i have some spare time to continue working on the car.