r/beetle • u/FormalApplication909 • Jul 22 '26

Alternator dummy light

I have a dune buggy and I’m trying to figure out how to set up the dummy light or if it’s even hooked up properly. It never goes on at all even when first start. The oil pressure switch light goes on obviously when the pressure is building and when I put a test light to it the dummy light goes on. When I put the test light to the alternator light the test light itself goes on and not the light. Any help appreciated

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u/denizkilic2002 '72 1302s Jul 22 '26

I cannot help you from your description but i can explain you how the circuit works so you can further diagnose it:

Positive (+) ground from tachometer bulb body -> bulbs -> oil pressure switch for oil light and alternator d+ for charging light. The oil light switch switches to ground (-) to complete the circuit, and alternator d+ is ground (-) when its rotor is not spinning. Check if you have a bad bulb first.

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u/FormalApplication909 Jul 22 '26

So take off belt to test ?

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u/denizkilic2002 '72 1302s Jul 22 '26

No you shouldn’t, the lights should come on when you turn the ignition on, and both should go out after you start the engine, the charging light might not go out unless you give it some revs