If cleaning and tightening doesn't help, turn on the head lights so some current is trying to flow, then start right on the battery terminals and measure the voltage. You should find 12.6 volts if it's fully charged. Next, move one meter probe from the post to the cable clamp. You should have exactly the same voltage. Now move the second probe from its post to the cable clamp. Continue moving each probe down the line until you find the spot where the voltage is noticeably lower. That may be only a few tenths of a volt but that is significant. The point where the voltage is different is the point of the bad connection.
For the negative part of the circuit, follow the smaller black cable from the battery post to the body. That connection is notorious for rusty and loose connections and it is the one that will affect stuff inside the car.
For the positive part of the circuit, follow the smaller cable to the fuse box. Check the two nuts there to be sure they're tight, and there might be a large bolted-in fuse. Be sure that is tight too.
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Saturday, September 22nd, 2012 AT 1:43 AM