The battery light will come on intermittently

MOUNTAINEER1977

MEMBER
2003 FORD WINDSTAR
6 CYL
2WD
AUTOMATIC
81,000 MILES

I have a 2003 Windstar and the battery light will come on intermittently. It will run fine. You stop and restart and it will clear. The battery and alternator were replaced last year. I have yet to be able to catch it where I can take a volt-ohm meter to it. Is the alternator failing again? The last one just completely died. It didn't give any warning.

5 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

It may be going out. Did you use a high quality replacemnet or a less expensive unit? The chaper ones are exactly that. Cheaper. First check all connections at the alt and battery to be sure they are clean and tight, this can cause intermittemt charging issues. If it continues and all connections are good, it sounds like the alt

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Tuesday, May 4th, 2021 AT 5:21 PM

MOUNTAINEER1977

MEMBER
3 POSTS

It was from Advance. It was the only one in stock so it was running about the same price as the other stores. I have done a quick check on the connections but not good one. Will try that one next.

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Tuesday, May 4th, 2021 AT 5:21 PM

MOUNTAINEER1977

MEMBER
3 POSTS

I redid the connections. I thought it helped but it came on again. I checked the voltage at the battery with the alternator light on, it was 14.5v. I restarted the vehicle, light went away. It was putting out 12.5v with the heater, lights, etc running but no light. Any ideas?

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Tuesday, May 4th, 2021 AT 5:21 PM

2CARPRO JACK

MECHANIC
11,533 POSTS

Sounds like the regulator in the alt may be bad.The light may be coming on due to overcharging (almost 15 volts). Be sure the ground on the engine is clean and tight.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

This guide should help test it.

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Tuesday, May 4th, 2021 AT 5:21 PM

SQM

MECHANIC
6,383 POSTS

Faulty voltage regulator in the alternator can overcharge the battery, it is possible for the regulator to be not stable and fluctuate on the output. Which could explain the intermittent battery light.

It can also be due to a loose ground strap on the alternator. Make sure that ground is secured and clean of any corrosions.

https://www.2carpros.com/articles/how-to-replace-an-alternator

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.

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