Dear Jim,

I drive a 1991 Chrysler New Yorker, and something is wrong with the battery charging system. My repair shop has replaced the alternator twice now, but the results are the same. The battery still keeps running down while I drive, and I've had to get jump-started several times over the last month. The guy at the shop says the alternator and regulator replacement should have worked, and he can't find any bad wiring anywhere. Any ideas what's going on here, Jim?

-- Dave Mauer

Your problem, bro, is similar to the voltage gauge question someone asked last week, but very different at the same time. That person was having no trouble with the charging, even though the dashboard gauge was telling her differently. You're having real charging difficulties, so we already know there's something more serious going on. Once again, the solution lies in knowing a little bit about how your particular vehicle is put together.

This kind of bad charging situation is often the fault of the voltage regulator. If your mechanic replaced the car's alternator twice, he's probably assuming that he replaced the regulator twice as well, because the regulator unit is usually part of the alternator.

Not true with a '91 New Yorker. The regulator isn't built into the alternator, it's integrated into the engine control module (ECM) -- an electronic device more commonly known as the car's computer. As we've talked about in the past, the computer controls all kinds of crucial systems in the car. Yours might be working perfectly at everything else it does, but the regulator part can still be burnt out. Get the ECM checked, bro. Given the problem you're describing, it's hard to imagine what else could be causing the charging failure.

Tip of the Week

It's amazing how much the weather changes over just a couple of months. Day and night temperatures are dropping fast these days, and your vehicles can already feel the difference. Now's the perfect time to winterize and help your car, truck or SUV with the cold-weather adjustment. Flush the cooling system and replace the coolant; replace windshield wiper blades and washer fluid; test the battery and replace it if it's old; keep the tire pressure up (air contracts in the cold); check the lights, heater and defroster; get a brake check; keep the gas tank at least half-full to keep moisture out of the fuel line. Your vehicle will be ready for the chill, and you'll have peace of mind.

Buffalo Jim, owner of Allstate Auto & Marine Repair in Las Vegas, writes a weekly column. Send your automotive questions to him at buffalojim@lasvegasniftynickel.com. If Jim picks your question to answer in Nuts & Bolts, you'll also be the proud recipient of a deck of official Buffalo Jim playing cards, presented in a classy, tin box bearing his hairy image.