I recommend a volt gauge. The idiot light doesn't always warn you when there are problems with the charging system. Our cars leave us stranded when they quit charging.

First, you have to develop a habit of looking at the light when you first turn the key before starting it. That is the lamp test mode. When one doesn't light, that's a problem. I'm just not able to muster that much discipline about staring the car.

If you spot a gauge in the yards or on the auction sites, be sure it comes with the bezel and the three rubber pads. Here's an easy way to install one:

Simple Voltmeter Wiring
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Art Benstein near Baltimore

"When I read about the evils of drinking, I gave up reading." - Henny Youngman