Battery not charging, which fuses should I check?

BEASTY83

MEMBER
2000 FORD MUSTANG
3.8L
6 CYL
2WD
AUTOMATIC
2,100,000 MILES

I just got a refurbished alternator, and my car still does not charge. So, I went back to the store and had them test my old alternator and it was good, so I returned the refurbished one and now I was thinking of the fuses that I would need to check. Could you please let me know which ones I need to check or what I need to do now?

1 Reply

BORIS K

MECHANIC
799 POSTS

Hello,

Please see the diagram below of the charging system.
Ensure that both fuses, alt fuse(20A) and charge indicator lamp fuse(5A) are good.

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

Next check that there is battery voltage at the B+ terminal, black/orange wire, at the alternator.

This can be done by using a voltmeter or test light.

How to:
https://www.2carpros.com/articles/how-to-use-a-voltmeter
and
https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Check that there is battery voltage at terminal A, yellow/white wire, at the alternator
With ignition on, engine not running, we should also have battery voltage at the I terminal, green/red wire, at the alternator.

If all these inputs are given and the alternator is still not charging, i.e. charging lamp does not extinguish, then next check voltage at the B+ terminal with engine running. Are you getting battery voltage or readings of around 14V?

Please also try and connect a battery jumper cable from the alternator to a good chassis ground, see if this makes a difference.

Hope this helps.

Cheers, Boris

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