Yes check for a 5 volt pulse.
They can malfunction sending 12 volts to the gauges which will burn out the gauges. I just replaced both the VL and gauges on my friends 70 Cuda. They can also just stop working altogether.
The condenser stores a charge for the gauges.

72 Satellite Sebring Plus 440, 72 Dart 5.9 4-spd, 68 Valiant, 73 W200, 78 D100 sb, 78 D200, 98 DAKOTA, .
Moparmarks Parts & Restorations
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Grand Jct. CO
970-261-7039
http://moparmark.com/
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