Battery light on Jaguar S type 3.0
 

Ever since i had gotten my car there always has been the battery light turning on right after the needle had settled down under 1000 rpm. i have replaced the battery and the alternator, but none of that has worked to turn the light off. charging is fine, i haven't had a dead battery and the car has always started strong. Help!

Did you replace the alternator with a cheap aftermarket one? These cars need a good charging system. If it is not charging exactly what it should be you will have problems.

Check ALL connections also. Clean both the positive and negative cables and any other grounds.

FYI Some people have even reported that some aftermarket alternators cause the battery light to come on regardless of the charging voltage.

Aftermarket often don't interface to the PCM properly so you get the light on. I don't know if it matters, other than being annoying and I suppose it would mask any future fault that otherwise would have put the light on.

yeah I'm guessing the ultima brand from O'reillys isn't a quality item. Thanks guys! I'll be looking into that and update as soon as I could get a new oem one.

Any chance you have the old original one? If you can rebuild your original that seems to work best.

We have had several people replace the alternator and got your exact problem. Can you tell if it's charging? Measure the system voltage with the car off and with it running. You say it appears to be working fine.

The problem is interfacing the alternator to the Jaguar electrical system. So you can be charging fine and still have the red light on.
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