89 Corolla break and battery check light


Old 10-19-04, 08:31 AM
Thread Starter
Join Date: Nov 2003
Location: USA
Posts: 155
89 Corolla break and battery check light


The car worked fine until a few days ago when she did a hard break. Then she noticed the battery check light came on.

I did the brakes a year ago. Check all the fuses in the drivers side kick panel and the fuses by the battery in the engine compartment. All seems ok (used a DMM continuity test). Visual check of alternator cables and battery cables seemed OK. I forgot to check the alternator belt to see if it broke off but then why would the brake lights come on.

Used the DMM on the battery terminals when the car is on and it read 12.5 V. This suggests the alternator is bad (the alternator was replaced two years ago). But why did the brake warning light come on?

Suggestions? Thanks.
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Old 10-19-04, 09:19 AM
Join Date: Jan 2002
Location: Chicago
Posts: 1,915
Funny things happen when there is not enough power to supply. Check the alternator belt and see if it spins first. Also check the wiring and connections to the alternator, and any ground straps you may have. If everything checks ok take the alternator out, and have it checked ( you should also be able to measure the output on the car, withough taking it out). Alternators fail, especially the cheaply rebuilt ones.
Old 10-19-04, 02:56 PM
Join Date: Jun 2002
Location: Long Island, NY
Posts: 1,531
The charge lite proves out the brake lite. So if the charge lite goes on the brake lite will be on too. Their is a diode between them to prevent the brake lite if activated from turning on the charge lite.

Most likley a bad alt.
Old 10-21-04, 09:09 AM
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Join Date: Nov 2003
Location: USA
Posts: 155

Thank you for all your suggestions. I replaced the alternator and both check lights went out. Tested charging with DMM at battery terminals and is getting 14.4 V.

Thanks again.

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