A band-aid won't heal this problem...

Dear Car Talk

Dear Car Talk | Apr 01, 1990

Dear Tom and Ray:

My problem concerns one of my dash lights. When I'm traveling at night, the red "charge" light floats in and out very lightly. It gets stronger if I use the heater, the defroster, the radio, or the bright lights. I've stopped at two gas stations, they've both checked the belts, and told me it was nothing to worry about. I recently put a band-aid over the light so I wouldn't have to look at it, but when I took the band-aid off, the light was still flickering. Please tell me what my problem is.

RAY: The "charge" light comes on for one of two reasons. Either you're not getting enough power from your car's charging system, or you've almost paid off your credit cards and it's time to start running up the bills again. Since you've probably just charged your new spring wardrobe, we'll assume it's the car.

TOM: Electrical devices--like the lights, heater or defroster--require electrical power. When the engine is running, that power is produced by the car's charging system, which consists of an alternator and a voltage regulator. If either is malfunctioning, the charging system won't be able to keep up with the demand for power. That's when the charge light comes on. The less the system is able to keep up, the brighter the charge light gets.

RAY: The power from the charging system must be both the correct number of volts and the correct number of amps. It's possible to have enough of one, and not enough of the other. Find a shop that can test your charging system for both volts and amps--don't go to the places that can only test for belts like the two gas stations you tried!

TOM: I like the band-aid idea, Shirley, but my guess is that it's going to take a new alternator or voltage regulator to heal this problem. And if you don't get to it soon, you'll be needing jumpstarts in the morning.

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