Bizarre Cluster issue

[66ValiantFullCustom]

I have a ‘66 valiant. About a week ago my fuel gauge went from perfect operation to stuck on empty. My dash lights (LEDs) are also having a weird problem where one half of the cluster is bright, but the other barely has any juice. I accidentally discovered that if the key is off and the turn indicator is on my entire dash lights up beautifully.

any thoughts?

 

[67Dart273]

I'd start with grounding. I don't know what your cluster looks like. Are there two boards? Both must be grounded together, to the cluster housing if it's metal, and to the dash frame. Most OEM clusters do NOT have decent grounding. Most depended on cluster mounting screws which is a poor deal.

If you can post a decent picture of the rear, I likely can give you some ideas

 

[66ValiantFullCustom]

I'd start with grounding. I don't know what your cluster looks like. Are there two boards? Both must be grounded together, to the cluster housing if it's metal, and to the dash frame. Most OEM clusters do NOT have decent grounding. Most depended on cluster mounting screws which is a poor deal.

If you can post a decent picture of the rear, I likely can give you some ideas

Single circuit board in pretty much immaculate condition. I have also already grounded the cluster connecting 12ga via self tappers to the dash supports

 

[Scody21]

LED bulbs draw less current than old school bulbs thus having issues like your discribing. There was a thread talking about this 2-3 weeks ago...

 

[Scody21]

Here’s one

LEDG vs Halogen Incandescent headlights

 

[Scody21]

And another

Erratic Gauges

 

[Scody21]

And one more

led dome lights

 

[67Dart273]

Single circuit board in pretty much immaculate condition. I have also already grounded the cluster connecting 12ga via self tappers to the dash supports

You may have installed a ground wire but that does not mean it is "grounding."

 

[RedFish]

Turn circuit could provide a backfeed ground path when there is no power on it.
The ground path for limiter and lighting starts with screws that attach the circuit board to the housing. Your board has only 3 screws and one at upper middle isn't on a ground trace. Pitiful design. Other model boards have a screw beside nearly every bulb socket.
You can add a ground wire with ring terminal at two screws. The screws aren't really long enough for ring terminal and a toothed washer. They are easy to strip out too. Anyway... even if you add a ground wire to somewhere else on the housing and/or circuit board, the copper pads and screws you have in 2 places need to be clean and snug.