X5 alternator bad?
 

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

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.

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.

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?

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.

Memorized :)

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

Legend! Thanks muchly! Handy thing to have

Glad to help!

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

Sorry I didn't mention, yes white the car is running it's at battery voltage high 11's low 12's.
Has anyone just replaced the voltage regulator before?

If those are your numbers, your alt is flat. To confirm the test, add an extra load such as AC, rear window def, and seat heaters if equipped. The voltage should go up. If not, the alt is dead. I am not sure of how many members have rebuilt the water cooled alternator, but I do know it was more of a pain than to just get a rebuilt unit. A lot of people have said that once it was buttoned up, a few months later, water entered its way from the front when driving through a puddle or what not and the contacts end up getting corroded. I mean it is easy enough to change, just not quite sure how cost effective it really is compared to having the alt rebuilt.

At idle, I would expect the alternator to be anywhere between 13 and a half, and 14 volts - or somewhere in that neighbourhood.

If it's not, then the charging circuit is cactus.

Ahhh...Australianese. :bustingup

:)

The full technical term is "cactus fuckti", but you know how we love to abbreviate things...

Unlocked my cluster last night. What a beauty! Some pretty cool nerd stuff going on there.

Where do you guys find good prices on alternators for us.

Pick N Pull or an Alternator / starter repair shop.