Gauges not working. Need help

[kenicb]

71 Charger.

temp gauge, fuel gauge, and Ammeter have stopped working.
as per the 71 service manual, I tested the voltage limiter with a test lamp on the back prongs of the gauges. The test light pulsed as it should. So voltage limiter is working.

The other option in the service manual is vague and says to check for faulty wiring or a bad ground from the battery. Can you help me understand what to check next please?

I went to the alternator. one of the field terminals (green wire to the voltage regulator) is loose and won't tighten up. Will this affect the gauges?

all light bulbs and turn signals are working. the 3 gauges do nothing.

thanks so much. God Bless

Keni

 

[tpodwdog]

ground the dash panel !

 

[bigmanjbmopar]

Check out all the grounds like dog said and yes a loose connection at the alt could cause some issues with the gauges.

Here is the wiring diagram for your car. helps if you can print them out. there is also a guy on ebag that sells large laminated versions. Good Luck!

http://www.mymopar.com/downloads/1971/71CoronetChargerA.JPG

http://www.mymopar.com/downloads/1971/71CoronetChargerB.JPG

 

[kenicb]

thanks so much for responding. I was checking the gauges with a 9 volt to see if they still worked. The temp and fuel both moved when I grounded them. So i think what you told me is a good suggestion.

Where do I connect a ground to the PC panel? Thanks again

Keni

 

[kenicb]

here's the update.

I replaced the alternator and Voltage regulator. Then pulled the instrument panel out and found the problem for the ammeter. The wires were loose. I bypassed the ammeter as it was pretty crispy at the connections from something that must have shorted long ago. Installed an aftermarket voltmeter instead.

I also cleaned all the copper on the control board, replaced all the bulbs and added a grounding wire as you suggested. This did the trick. Both the fuel gauge and the temp gauge operate correctly now.

thank you so much for the help. Godspeed

Keni