Q: My battery warning light comes on and then off again repeatedly.

asked by on February 06, 2017

Driving on the highway, wet roads, my battery warning light came on. The headlights dimmed and the blower fan slowed. Soon after, the ABS light, then the emergency brake light, then the trac light. Then the gauges zeroed and stopped working along with all the lights. The car was stuttering (assuming I was driving on the alternator output alone). I took the battery out and it tested as bad so I replaced it. I was still seeing the battery warning light so I tested the output of the alternator at warm idle. The output was between 14.5V and 15V. Now, after driving it home, I'm noticing the battery warning light comes on, then goes out repeatedly. I'm thinking a loose connection somewhere but I don't know where to look. I should also mention that yesterday I replaced a rear brake wheel cylinder. I am not sure if the wheel sensor on the side I replaced the wheel cylinder could be linked to this problem.

My car has 277000 miles.
My car has an automatic transmission.

Hi There, It sounds like you may have a weak connection or a short somewhere causing the excessive power draw on the electrical system. You may also want to check the voltage regulator to see if it is allowing the alternator to charge at a consistent rate as tested. In the event that it is working intermittently, this may cause the charging of the alternator to become erratic or inconsistent resulting in random power surges as you describe.

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