2003 4.4i with ABS lights on plus battery

[Skyline]

Stevo; It appears the battery is OK, and from he voltage shown when running, the alternator is working. But as already stated, these are fussy cars, with very sophisticated electronics, and yours is telling you it's not up to snuff. It's time to throw in the towel, and either bring it to a dealer or a good specialty shop that has some better diagnostic equipment. If you're looking for an independent shop, the very first question should be: 'Do you have an Autologic with up to date BMW Software". If the answer is no, move on. Once they sort the battery light, ask them to see if the Autologic can communicate with the ABS module. If the answer is no, tell them to NOT fix it. If it's a bad sensor, that's up to you, but likely not crazy expensive.

Either the ABS problems will solve themselves when all voltage issues are fixed, or they won't. If they don't, often the module is completely out to lunch. While it could be a sensor, if its the module, you can either: Put in a new part, then have it coded, ($1,500 part.). Put in a used part, and have it coded, ($750 part). Or send your module out to one of the rebuilders on eBay. If you're lucky, $100, and then recode. If you're not lucky, another $400 and they'll send you a rebuilt unit. No matter what, the unit will need to be coded. But to attempt this with a battery light on is silly; these cars are known to throw the trifecta lights when voltage is not perfect. Sort that first.

The ABS module in the X5 is in a very bad spot. It's about a minute to remove from a 5 series, but on the X5, you need to remove the left side headlight, and the whole assembly with the oil filter, power steering reservoir needs to be moved aside. Given the location down below the headlight, mine was completely filled with muck...no wonder it failed.

[Stevo96]

Thanks skyline, I also think that is the next step but I should mention I've just checked the voltage coming from the alternator and it isn't steady, it's jumping from 15v down to 7v, I'm assuming this is the voltage reg on the alt, I'm guessing because it isn't steady it's throwing the battery light on.. Maybe that's the first / cheaper option to replace the regulator.. It's funny that I'm getting a steady voltage at the battery end but unsteady from the alt to the ECM.

[Stevo96]

I measured it on the blue wire coming out of the alt and going to the ECM, I traced it up to the top of the engine, the wires join in a plastic box under the engine cover. I Was torn whether or not to replace the alt or the VR, I guess the safest option is to just replace the alt, I think I'm looking at $500 on eBay unless anyone knows of a cheaper option? I'll report back once it's fitted-now off to remove the alt, this should be fun!

[Stevo96]

I don't suppose someone wants to check their voltage coming from the blue wire on their alternator for me just to see if theirs fluctuates like mine? I want to make sure that's my problem before I purchase an alternator..

[Stevo96]

The car is now in with the BMW specialist, I should find out later today what the issue is, I asked them what they used and they said Pro logic or something like that.

[Stevo96]

OK, the garage has rang to tell me that it's the alternator - it has an intermittent fault hence the varying currents going back to the dash light, they wanted $2K for the new alternator fitted, i'll be buying one from a scrapper for $300 and fitting it myself shortly. Once that is fitted i'll have the ABS lights cleared and go from there... hopefully the new alt will fix the ABS lights, fingers crossed.

[Stevo96]

Basically because of the price.. Do I need a gasket for the alternator?

[Stevo96]

Update, I relaced the alternator today. Battery light and abs lights still on. Battery is charging fine at 14v. I'm peed off as the garage I took it to said "it took us a while to find it but your alternator has an intermittent fault" charged me $200 and that's that. I'll be going back to the garage on Monday for a refund as that obviously isnt the problem. I've read it could be the ignition switch? Or maybe even the cluster.. The ABS lights are still coming up with the same error "brief power interruption".

[Stevo96]

Yes I had checked all the cables previously. I'll check for the varying voltage again next. What's annoying is that I paid a BMW specialist to tell me what was wrong so that I didn't have to waste cash throwing money at parts I didn't need.. I'm wondering of it could be the wiring from the alt to the computer, I'll check anyway and come back to you.

[Stevo96]

I've just checked the wire going into the cluster, it looks like someone has been here before as the screws holding the cluster in were missing. Anyway, I'm getting 14v at pin 3. I believe this should be turning off the battery light... New cluster?