Alternator or Voltage Regulator Problems?
 

Hi everyone I was wondering if anyone has experienced this issue with their E53 before. To start, I have an 04 4.4i X5 with 128k miles.

On Monday when I drove the car, I was stuck in stop and go traffic and then all of a sudden my music cuts off and then the nav screen turned off and the hvac also shut off, when this happened the trifecta of lights illuminated on the dash (Brake, ABS, & 4x4) with the following TransFailsafe Prog. message and the cycle of the nav screen and hvac turning off and back on continued with the lights and message and then Engine Failsafe Prog also displayed and thats when I pulled over and shut the car off.

After waiting for a few minutes I turned the car back on and there were no lights illuminated and no messages for about 10 minutes, but since I was stuck in traffic still it happened again, then this time the instrument cluster displayed the message DSC / 4x4 inactive and transfailsafe prog and the SES light came on. When this happened I again had to pull over and shut the car off. When I turned the car on again all lights disappeared and I got full power back until it happened again for like the 3rd or 4th time. This time I waited until the traffic cleared and I turned the car on and all that was left was the SES light and 4x4 light and I flying down the freeway to make it back home which thankfully I did.

So yesterday I tried to replicate the issue at home, I went into the hidden menu feature and saw that just on battery power it was reading 11.7V. When I started the car it was reading 13.7V so I thought it was decent but I was looking for 14V. When I was simulating stop & go traffic I was getting a range of 13.5 - 13.7 volts on the instrument cluster. Then for a moment I felt a little shuddering and I saw on the instrument cluster it said 12.4V, but it went back up to 13.7. Then I drove around the block and when I got back to my neighborhood I was again simulating stop & go traffic and the instrument began displaying 13.8, then 14.0, then 14.5, then once it got to 15V the music and nav screen shut off, and the HVAC cut off and I believe it got up to 16V and thats when the trifecta of lights came back on and the message TransFailSafe Prog. came back on. So I drove it back up my driveway with a sever decrease in power and I turned it off. Turned it back on and it was running between 11.7 - 12.8V and it kept fluctuating between those two.

Sorry for this post being so long by the way. I saw on YouTube an X5 had these exact same symptoms and he said it was the alternator so before I go buy a new one what are you thoughts? Have any of you experienced this before? I'll attach some videos that I recorded documenting the symptoms. I would greatly appreciate your guys' help with this! And I am waiting for my INPA cable to come in so I can run the computer and see what codes are stored in the car.

Thanks in advance for your guys' help!

Hmm guess the Youtube hyperlink didn't work, but here are the links to the videos I recorded:
https://www.youtube.com/watch?v=diJ90jpr_x8
https://www.youtube.com/watch?v=srcWJCZU6-4

Certainly looks like a voltage problem. If you are sure your battery is within 2 years old and all the connections are good, I would guess the alternator is the issue. Some members have replaced the voltage regulator and there are some good write-ups on here.

https://xoutpost.com/bmw-sav-forums/...0i-01-a-3.html

Exact symptoms of worn brush/ slip ring on the alternator. I used the valeo kit for $20 to refurbish mine. If you have Bosch you can prob replace the regulator vs entire alternator but first check your cables for a weak connection at ground and the b+ under the hood.


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Classic alternator (voltage regulator) symptoms. I replaced mine with a cheap eBay unit. Works, but I don't recommend it as I will be replacing with a new Valeo after replacing the valve cover gaskets. The oil leakage causes the regulator you fail over time.

Oil was what killed mine. Not really the regulator though, the slip rings get coated and the brushes can't get full current to the field windings at low rpm.


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Over voltage. I actually got error codes for it.

$20 direct from bmw voltage regulator. Few hours labor and I’ve been good for 4-5 years now.

Thanks for all your replies! So my theory that its something related to the alternator is correct. I checked my alternator today and I don't see any oil or debris attached to it so I think it should be ok. Would it be best to just try and replace the voltage regulator or should I replace the whole unit since I will be pulling out the alternator anyways?

Thanks for your reply! I am now leaning towards just replacing the voltage regulator since you said you got error codes and over voltage which is what I am currently experiencing with my car and it is way cheaper to replace just the regulator.

What kind of codes did you get? Did the codes go away when you put in the new regulator or did you have to clear them with INPA?

Sounds every similar to what I dealt with. And I meant to say that I got an “overvoltage” error when scanning for errors with INPA. It showed my voltage spike to 15v and take out all sorts of other computers as fault protection. So it time stamps when overvoltage happened. And time stamps matched up identical with abs computer going down for example.

I don’t remember anymore, but I have Inpa, so I never wait for codes to go away, I reset and wait as a habit.

Tips from memory. My tool Arsenal is pretty advanced, but I don’t remember needing anything special here. Literally beers and chilling which my friend the whole way.

This is a very easy job on the 4.8is. Remove intake stuff. Remove electric fan. Takes 5 min. Disconnect neg battery terminal. Or use a kill switch, best mod for my car ever, by the way. Then remove duct for alternator, then remove belt. Then unscrew alt, pull out a bit and unbolt power wire. Twist turn, don’t slam the radiator. Put cardboard in front of it to be safe. Alternator out. Remove voltage regulator. Polish the copper/brass looking slip ring. I used this polishing cloth, but 3000 grit sand paper worked faster. I managed to spin the alt with my drill. I forgot how i rigged it up, but it made polishing the ring easy.

Inspect new regulator. Do not engage anything on it, or your install will get a lot harder. It’s sorta trick how it engages when you install it. You will see what I mean when you do it. I forget exactly, but you have to make the brushes contact, after you bolt it on the alt. Don’t push shit, or you will be sitting there putting the brush and spring back into the regulator. No fear after it’s bolted to alt. Then install. Start car and monitor voltage.

I was paranoid for a few days. I have never had overvoltage before, so this felt like an experiment. Well no issues since. 30k miles now. Went from crazy shit, to why the F..k was this so cheap to fix.