Gauges Die w/ Headlights On.

[domdart]

Going to and from Carlisle this weekend, I turned the headlights on while going through the tunnels on the turnpike. The temp gauge and fuel gauge both went off when I turned the headlights on. They came back about a minute after turning the headlights off. I have a 68 Dart. I replaced the headlight switch because my dash lights were not working. I ran a ground to the steering column from the new switch. The dash lights still did not work. Then, I connected a tach to my inst fuse and the dashlights worked temporarily. The dashlights did not come on in the tunnels. That is the first time I noticed them not working. Any thoughts on this problem will be greatly appreciated. Thanks FABO.

 

[Oaktree]

Sounds to me like a bad (ie-high resistance) ground on the cluster. Kinda sorta works with just the minimal current drawn by the gauges, but when you add the current for the dashlights not so much.

 

[67Dart273]

^^YES. Add a pigtail ground wire from the cluster somewhere to the dash frame. "For now" try loosening/ tightening the cluster mount screws

..........EDIT........Are you saying the gauges actually quit, or that the LAMPS for the gauges go out?

The dash lighting is a little bit of a trick

The headlight switch has TWO power sources, one for only the headlights.......and the other comes from the tail fuse, and powers tail, park, and dash lamps.

That power goes through the switch, through and OUT the dimmer control AND THEN goes down to the INST fuse on a tan wire, through that fuse, and out to the dash lighting on ORANGE wiring.

You need to check both ends of that fuse, with a meter, WITH the park lights on, and while manipulating the dimmer control. You should have varying voltage there.

Do the "non cluster" lamps work, like, radio, heater bezel, etc?

Could again, be cluster grounding, dirty / corrosion at the sockets / PC board and of course the lamps themselves

 

[domdart]

^^YES. Add a pigtail ground wire from the cluster somewhere to the dash frame. "For now" try loosening/ tightening the cluster mount screws

..........EDIT........Are you saying the gauges actually quit, or that the LAMPS for the gauges go out?

The dash lighting is a little bit of a trick

The headlight switch has TWO power sources, one for only the headlights.......and the other comes from the tail fuse, and powers tail, park, and dash lamps.

That power goes through the switch, through and OUT the dimmer control AND THEN goes down to the INST fuse on a tan wire, through that fuse, and out to the dash lighting on ORANGE wiring.

You need to check both ends of that fuse, with a meter, WITH the park lights on, and while manipulating the dimmer control. You should have varying voltage there.

Do the "non cluster" lamps work, like, radio, heater bezel, etc?

Could again, be cluster grounding, dirty / corrosion at the sockets / PC board and of course the lamps themselves

The gauges quit. I added the dash light problem just to give as much info as possible. I thought the issues might related.

 

[67Dart273]

They could be. I would certainly start with grounding. As I said the quickest simplest "for now" would be to tighten / loosen the cluster mount screws. With the problem manifested, this should tell you quickly if you are on the right track.