1973dusterkid
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It is on a 73 duster non rally dash its a blue wire with a white strip its the one beside the fuel sending unit.
Thats power supply directly from ignition switch hot in run to the instrument panel. Supplies 12 volt to gauge limiter, park brake indicator lamp, oil warning lamp, varries from model to model.
Is the wiper switch chassis grounded ? Original mount in metal provided that .
Is there a ground wire in/with the windshield wiper switch/plug
The switch is actually grounded by the switch housing when it is installed into the cast cluster housing. Another words, internally grounded. What is your new custom dash made of?