X5 alternator bad?

[Jeffatpm]

Hello all,
I think my alternator or at least voltage regulator has gone bad.
I changed my aux fan and a few days later the battery light came on, the car drove until the battery was dead.
I've checked the fuses in the glovebox, the passenger rear cargo area, the block by the spare tire and the passenger bay one, any others I've missed?

I'm thinking to try replacing just the voltage regulator first, anyone know any other tests I should try?

Any thoughts or comments, things I've missed?

Thanks Kevin

[TwinTurboGTR]

Well, see how many volts you are pulling from the system. If it is nothing, then the alternator isn't any good. I am assuming the 02 4.4 is the problem. Those are watercooled alternators. The swap out the regulator isnt exactly easy. Depending on the mileage, you may be better off having the unit rebuilt.

[ants_oz]

Yep, I'd be putting a multimeter across the battery when the vehicle is running, and seeing how much power is getting there.

Diagnosis comes before throwing parts at a problem.

[g300d]

Have you unlocked your cluster test mode? Test 7 or 9 will give you battery voltage.

Very convenient first step to check battery and charging system status without having to open the hood/trunk. Though if the battery indicator already lit up, dollars to donuts its the alternator in my experience.

[ants_oz]

Originally Posted by g300d

Have you unlocked your cluster test mode? Test 7 or 9 will give you battery voltage.

Very convenient first step to check battery and charging system status without having to open the hood/trunk. Though if the battery indicator already lit up, dollars to donuts its the alternator in my experience.

Eyes light up...

Being a new BMW owner, I'm not familiar with this test routine. Are you able to point me to a resource?

[g300d]

Sure! I suck at instructions so let me look for the link. In the meantime, get the last 5 digits of your VIN ready, you'll need it to unlock the cluster.

[ants_oz]

Originally Posted by g300d

<snip> get the last 5 digits of your VIN ready, you'll need it to unlock the cluster.

Memorized

[g300d]

Haha same here, because I buy parts for it so often!

Here ya go, a good write up with explanations for each test mode:

unlocking cluster OBC

[ants_oz]

Legend! Thanks muchly! Handy thing to have

[g300d]

Glad to help!

Yes indeed, very handy! I monitor battery voltage and real-time coolant temp often with this (tests 7 and 9).