Fuel and temp?

[Drew67coronet]

Okay so I've got a 1967 dodge Coronet
My temp and fuel gauge do not work, my oil light and ammeter DO work. I've checked the sender at the tank the ohms were on spec I put a brand new ground bare metal to bare metal on the gas tank and frame. Brand new instrument voltage regulator brand new circuit board from classic industries. I've cleaned every single ground in the engine bay, I've cleaned the bulkhead connectors. Put in a brand new temp sensor checked all wiring for bare spots or burns. Neither fuel or temp gauge peg when I ground sender wire. Is it possible my instrument voltage regulator isn't getting power? Any advice would be appreciated.

 

[Fran Blacker]

Probably needs to be replaced, stuck open maybe. They make electronic ones now.

 

[turbine68rt]

Have you checked that all fuses are good?

 

[Drew67coronet]

Have you checked that all fuses are good?

Yes, the only one that doesn't work is the cigar lighter all other fuses are good

 

[beanhead]

You already did the "ground the sending wire" tests; good start. Refer to your FSM wiring diagram and turn the key to run, crawl under there and (carefully!) check for power before and after the regulator and you'll know for certain.
If nothing on the feed terminal, trace the power from point to point until you find the break.
Make sure the large multi-pin connector is firmly attached to the back of the instrument circuit board, and that all the pins are still attached to the board. Sometimes they get broken and you lose that circuit.

 

[Drew67coronet]

You already did the "ground the sending wire" tests; good start. Refer to your FSM wiring diagram and turn the key to run, crawl under there and (carefully!) check for power before and after the regulator and you'll know for certain.
If nothing on the feed terminal, trace the power from point to point until you find the break.
Make sure the large multi-pin connector is firmly attached to the back of the instrument circuit board, and that all the pins are still attached to the board. Sometimes they get broken and you lose that circuit.

Will do, I'll test the regulator In a bit and I put a brand new circuit board in and while I had the cluster out I checked for power at the muti pin connector all of them had power when I used the corresponding switches in thinking if I find that the voltage regulator is getting power I might just have two faulty gauges, which would be weird but not impossible. Thank you!

 

[Fran Blacker]

It could getting power, output needs to be about 5v. It isn't constant, there a bi-metal spring heats separates. Had one I could a ping and gauges would bounce.

 

[Drew67coronet]

It could getting power, output needs to be about 5v. It isn't constant, there a bi-metal spring heats separates. Had one I could a ping and gauges would bounce.

It's suppose to pulse right? 5 volts in a pulse. If it's getting that 5 volts then it must be the guages that are bad.

 

[Fran Blacker]

Not necessarily it could in the no voltage position or what's called open position. Don't hook 12 volts to gauges they go poof.

 

[Drew67coronet]

Not necessarily it could in the no voltage position or what's called open position. Don't hook 12 volts to gauges they go poof.

Why does it go to open position? It's a brand new one. Perhaps I got a faulty one?

 

[Fran Blacker]

If stays in the closed position you get 12 volts to gauges. Don't know how long it takes to burn them up. The gauges would go to full it suck closed. Look for 12 volts going into voltage limiter and no pulses of voltage out its the problem.

 

[Drew67coronet]

If stays in the closed position you get 12 volts to gauges. Don't know how long it takes to burn them up. The gauges would go to full it suck closed. Look for 12 volts going into voltage limiter and no pulses of voltage out its the problem.

Okay I'll check that when I get off of work. Thank you very much!

 

[Nacho-RT74]

----to test gauges:

you can use any source below 5 volts to test them. Just source the gauges studs with them. You can use a 1.5 volts batt, or maybe 2 1.5 batts in series. Maybe an USB power source ( which is 5 volts ). The gauge needles should move to whatever position the voltage source you send. If 5 volts will read to top of scale... if 3 volts, will be around half of the reading... and so.

You could even use a 9 volts bat, but just for couple of seconds, because more time could burn them.

pole on studs is irrelevant, either one

----to test Voltage limiter:

feed the input prong with 12 volts, and ground the chassis. The output prong should be measured with a test light or analog VOM ( multitester ). It can't be done with a digital one ). The test light or the VOM should read pulsating signals. No matter the speed, but willl be a pulsating signal. This pulsating signal is what makes the 5 volts average to the gauges.


IF voltage went bad IT COULD get burnt the gauges, depending on how it went bad. Voltage limiter is a points system which opens and closes at certain speed giving those output pulses. If points got stuck for whatever reason... missed ground, or burnt coil around bimetallic, will allow to feed gauges with 12 volts and burn the gauges.


the voltage limiter uses to be sourced from RUN circuit, but some cars are from ACC circuit. Normally cars with "idiot lights" ( oil ) and PCBs, get sourced the VL from the RUN circuit, getting the light and VL the same source. So if your Oil light is working ( it should work also with the pilot brake light on cluster ) it means your VL is suposselly also getting power

Dunno which VL gets the 67 Coronet but on this VL, the input is the middle prong, and the ouput is the left one

On this one, The input prong is the U shaped, and the output is the one alone ( female )

 

[Fran Blacker]

Nacho Thanks for rescue. I can't say very well how to diagnose the other than replace limiter.
Drew, keep us posted. Like to know what fixes your problem, thanks.

Upper limiter is in 67.

 

[Nacho-RT74]

yeah, well I just post how to diagnosis they are in working order, without mean they are working propperly. Usually if nobody touched the adjuster screw ( the one on backelite ) it should be on rate. Is hard to find two limiters with same speed pulsating signal. You can find slow pulsating signals for long time periods and you can find some with short time and fast pulses. Either one can be feeding 5 volts average.

 

[Durandal25]

Its hard to say, but have you have a chance to look at the back of the circuit board? They get corroded as hell and can cause this issue....little bit of CLR and a Q Tip will get that issue gone.

 

[Drew67coronet]

----to test gauges:

you can use any source below 5 volts to test them. Just source the gauges studs with them. You can use a 1.5 volts batt, or maybe 2 1.5 batts in series. Maybe an USB power source ( which is 5 volts ). The gauge needles should move to whatever position the voltage source you send. If 5 volts will read to top of scale... if 3 volts, will be around half of the reading... and so.

You could even use a 9 volts bat, but just for couple of seconds, because more time could burn them.

pole on studs is irrelevant, either one

----to test Voltage limiter:

feed the input prong with 12 volts, and ground the chassis. The output prong should be measured with a test light or analog VOM ( multitester ). It can't be done with a digital one ). The test light or the VOM should read pulsating signals. No matter the speed, but willl be a pulsating signal. This pulsating signal is what makes the 5 volts average to the gauges.


IF voltage went bad IT COULD get burnt the gauges, depending on how it went bad. Voltage limiter is a points system which opens and closes at certain speed giving those output pulses. If points got stuck for whatever reason... missed ground, or burnt coil around bimetallic, will allow to feed gauges with 12 volts and burn the gauges.


the voltage limiter uses to be sourced from RUN circuit, but some cars are from ACC circuit. Normally cars with "idiot lights" ( oil ) and PCBs, get sourced the VL from the RUN circuit, getting the light and VL the same source. So if your Oil light is working ( it should work also with the pilot brake light on cluster ) it means your VL is suposselly also getting power

Dunno which VL gets the 67 Coronet but on this VL, the input is the middle prong, and the ouput is the left one

View attachment 976091

On this one, The input prong is the U shaped, and the output is the one alone ( female )

View attachment 976088

Thank you for the very valuable Info. I have the first voltage limiter and it has a condenser shaped plug that feeds into the middle prong I have no idea what it is but I'll try to find a picture

 

[Drew67coronet]

 

[Drew67coronet]

Its hard to say, but have you have a chance to look at the back of the circuit board? They get corroded as hell and can cause this issue....little bit of CLR and a Q Tip will get that issue gone.

The circuit board is brand new from classic industries! It's very clean all dash lights work including turn signal indicators high beam gauge oil light brake light and ammeter

 

[Nacho-RT74]

That's a noise suppression condenser