Today: how to tackle some nasty battery cable corrosion.

Dear Car Talk

Dear Car Talk | Jun 01, 2009

Dear Tom and Ray:

I have a 1991 Ford F-150. You could use up this entire section of the newspaper on this hunk of junk. But perhaps you can just help me get it started. It won't turn over, despite numerous attempts. I've taken the battery to AutoZone, and they say it's good and it's fully charged. I even put it on the charger overnight to be sure. When I turn the ignition, it just grunts at me. After two or three grunts, all systems are unresponsive. Neither the headlights nor the radio will go on. Any ideas?

-- Steve

TOM: We'll assume that AutoZone is right, and the battery is fine. In which case, you have either a bad connection at the battery, or a bad ground.

RAY: There are two cables that run from your battery. One is the positive cable, which runs to the starter. The other is the negative cable, which is the ground. That wire runs to the frame of the truck, and from the frame, another wire connects it to the engine block (the engine sits on rubber mounts, so it has to be grounded to the frame by wire).

TOM: And after nearly two decades, those connections could be in worse shape than my brother's 401(k).

RAY: Or you could have so much corrosion around ANY of these connections that the resistance created by that corrosion is simply stopping the current from getting through.

TOM: So start with the terminals right at the battery. Give them a good cleaning with some sandpaper. If that doesn't fix it, follow the ground wire. Check all the ground connections, and clean or replace as necessary.

RAY: Or, as we like to say, you can "break new ground," and simply run new ground wires to the frame and the engine block. Getting yourself properly grounded ought to clear this up, Steve.

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