Join Date: Mar 2002
Location: Austin, TX, USA
Re: Bad Ground?
It could be a bad ground. Get a digital volt meter and measure the voltage between the battery (-) post (not the clamp), and the interior grounds (dash and chassis). You should see very little if any reading on the meter when you operate your accessories. If you're seeing more than 0.1 volts you've probably got a bad ground somewhere.
You can also repeat this test between the battery (+) and various hot spots in the car. Again, look for less than 0.1 volts drop when those accessories are on. If you see more than that, you've got a bad connection in the power feed for that circuit.
It helps to have a wire extender to reach from the battery to the interior. You may also need a helper to hold the battery connection while you test.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI