Battery Light-After Coolant Leak and Waterpump Replacement
 

The battery light on the dash is on all the time. Started after a massive coolant leak that sprayed coolant all over the engine bay. I have since replaced the water pump, coolant hoses and washed the engine bay of coolant residue (washed from the hose, not pressure washer).

The alternator was recently rebuilt. Still tests good. I have 13.8v with engine running. I removed the positive wire at the alternator and made sure the connection was clean and dry. I removed the computer wire at the alternator and made sure it was clean and dry.

The battery is newish. Tests good according to a load test. I have 12.6v at the battery, at the terminals under the hood and at the alternator.

Why else causes the battery light to come on?

I had a buddy that had something go haywire in his cluster that caused the bat light to stay lit even though alternator was doing its job.

Pull up the real-time vBat in the OBC hidden menu and drive around and confirm the vBat stays 13.5 ± .4

Usually when Alternator will output power but inconsistent, the bat light will blink. You wish to determine if the Alternator output is stable and the idiot light is in error.

The only way I suppose to know for sure is oscope reading to make sure all three winding are supplying power. I suspect a case could happen with an open ckt on one winding and the other two still output an AVG voltage that looks ok.

OP has a 2003 X5 4.4

Is the alternator water cooled in that engine? I think it might be...

OP any codes? Also plus 1 on looking at live data if you can

The alternator is water-cooled on this model and recently rebuilt. No codes related to voltage or battery (using INPA and ISTA).

Perhaps check the smaller red cable on the BST - this is known to come loose and cause a few issues.

The smaller of the two red cable in this image...

https://www.bimmerfest.com/attachmen...ry-jpg.473780/

Yeah - the melted one!

More pictures - https://xoutpost.com/1216165-post19.html

Make sure the alternator BELT is clean and dry as well.

Good point. I put a new belt on after changing the water pump as the old was was soaked. I will check that the alternator pulley is spinning properly. I think so since I have a consistent 13.8v with the engine running (from dmm, not dash display). I still need to monitor the dash display while driving.