not charging

[tomrad]

My son's 2003 Liberty has the battery light on, and I checked voltage with engine running, 11.5. I'm guessing alternator.
Original alternator, with 125k miles.
I understand the regulator isn't in the alternator?
Looks like the 136 amp one, from the pictures I've seen, the back is gray (160's are black, as far as I know). Any way to tell for sure? I don't see any obvious markings on it.
Now to buy one....any recommendations?
Thanks!

 

[LibertyTC]

At 125k that is some very good service life form the OEM (Denso ALt)
62316[/ATTACH]"]

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The photo shows the part numbers for googling them.
You could even probably find one at a salvage yard.
The PCM controls the charging so the above Denso works fine.

 

[Billwill]

Check the charging voltage right at the large lug on the alternator....this thick cable going to the positive terminal on the battery actually has a "fusable" link inside it....like a fuse.
There is a remote chance that this fuse may have blown due to a short to engine or while jump starting the engine. Check also that the small connector on the alternator is firmly connected.

With battery disconnected I would also re-plug the connectors on the PCM a few times in case of a dirty connector pin.
The voltage is regulated within the PCM so hence the need to check for a clean connection.

The Battery Icon on the early KJs also comes on if there is a problem with the Battery Temperature Sensor located under the battery but if there was a problem with this temperature sensor you would still expect to get about +13 volts across the battery with engine running.

But yeah probably time for a new alternator!

 

[tomrad]

Thanks, it was the alternator that failed. Easy to replace on these vehicles. I torqued the bolts as specified in the service manual, however, I just snugged the cable lug. The manual stated 115 in lbs, but I didn't think it needed to be that tight. New alternator has a lockwasher on the stud, unlike the old one.
Thanks again for the advice.