Why do my gauges do this?

[70383ChargerSE]

So I am working out the electrical issues on a 70 Dodge Charger. When I do not turn on my headlights, my factory gauges work. The second I turn on my parking lights or my headlights, the fuel, temperature and oil pressure all slowly peg to the maximum readings? Any ideas why this happens and what I can do to fix this?

Thank you

 

[BeepBeepRR]

You have something wired wrong. All of the gauges Fuel Oil and Temp run off the voltage limiter on the back side of the cluster. They are probably getting more than the 5 volts required to run them. You need to download a wiring schematic for your car and go through the wiring before you smoke your gauges. Also make sure your grounding is good. Engine to frame, Engine to Firewall, Cluster to dash, Dash to body. Grounding is very important.

Schematic A
http://www.mymopar.com/downloads/1970/70ChargerA.JPG

Schematic B
http://www.mymopar.com/downloads/1970/70ChargerB.JPG

 

[kiwigtx]

So I am working out the electrical issues on a 70 Dodge Charger. When I do not turn on my headlights, my factory gauges work. The second I turn on my parking lights or my headlights, the fuel, temperature and oil pressure all slowly peg to the maximum readings? Any ideas why this happens and what I can do to fix this?

Thank you

First place I would check is the foot operated dip switch on the floor - I'll bet that the wires and terminals have melted and are shorting to 'ground' - causing the loss of headlights.

 

[BeepBeepRR]

My thinking is that somehow when you turn the lights on you are putting 12 volts to the cluster on the gauge side.. Perhaps a wire is misplaced in the round connector that goes onto the cluster.

 

[kiwigtx]

My thinking is that somehow when you turn the lights on you are putting 12 volts to the cluster on the gauge side.. Perhaps a wire is misplaced in the round connector that goes onto the cluster.

Maybe someone has been screwing around with the dash wiring and put 12V where it shouldn't be?