Replace voltage regulator?

Has anyone replaced the voltage regulator on the alternator?

I got a code 5DF7 and D373 which points to a bad voltage regulator.

They do sell the part separately so there is no need for a whole alternator.

I see a DIY for the alternator replacement but nothing for the voltage regulator. I was wondering if it is easier to just replace the voltage regulator than the whole alternator on the M3?

From the S85 M5 forums, it is a 30 min job on their cars. Is it as easy for ours?

http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/193574-fyi-e60-m5-s85-valeo-voltage-regulator-alternator-2.html

Most people aren't aware of this option and end up replacing the whole alternator, so good for you for thinking outside the box.

Yes it's that easy. Same process since the alternator is almost identical. It's very straight forward, just be aware of the brushes in the regulator (that diy called them teeth). Don't let them pop out or you'll have a heck of a time getting the regulator assembly over the commutator. Good luck!

deansbimmer wrote

Most people aren't aware of this option and end up replacing the whole alternator, so good for you for thinking outside the box.

Yes it's that easy. Same process since the alternator is almost identical. It's very straight forward, just be aware of the brushes in the regulator (that diy called them teeth). Don't let them pop out or you'll have a heck of a time getting the regulator assembly over the commutator. Good luck!

Bumping an old thread, but is the the correct regulator? I'm replacing mine very soon. Thanks

Yes thats it.

deansbimmer wrote

Yes thats it.

Thank you so much! Just ordered and should be able to work on this over the weekend.


Has any seen any useful DIYs with pics accessing the E9X alternator? I've been searching for 2 days and only found the M5-specific thread posted above. If it's virtually the same I'll just use that one.

I am not sure you can get to the regulator without unbolting the alternator and moving it towards the radiator. Assuming that is true, here is a DIY covering that:

https://www.m3post.com/forums/showthread.php?t=1180343

One person in the thread had success replacing just the regulator. Most of us replaced the alternator.

Check your oil pan to frame rail ground cable on the drivers side near the header collector. They are known to rot and become ineffective.

pbonsalb wrote

I am not sure you can get to the regulator without unbolting the alternator and moving it towards the radiator. Assuming that is true, here is a DIY covering that:

https://www.m3post.com/forums/showthread.php?t=1180343

One person in the thread had success replacing just the regulator. Most of us replaced the alternator.

Check your oil pan to frame rail ground cable on the drivers side near the header collector. They are known to rot and become ineffective.

Thanks for the info!

deansbimmer wrote

Yes thats it.

The new regulator looks like it has only one brush whereas my old regulator has 2 brushes. Will this be a problem?

Thanks

RedScytheM3 wrote

deansbimmer wrote

Yes thats it.

The new regulator looks like it has only one brush whereas my old regulator has 2 brushes. Will this be a problem?

Thanks

The brushes need to be retracted or you can't install it over the commutator.

That's also part of the difficulty with trying to install a used one. You can't easily pull the brushes back enough to install the part.

deansbimmer wrote

RedScytheM3 wrote

deansbimmer wrote

Yes thats it.

The new regulator looks like it has only one brush whereas my old regulator has 2 brushes. Will this be a problem?

Thanks

The brushes need to be retracted or you can't install it over the commutator.

That's also part of the difficulty with trying to install a used one. You can't easily pull the brushes back enough to install the part.

Yes, I didn't eject the brush on the new regulator. The new regulator appears to only have 1 brush though, whereas the old one I pulled off my alternator has 2 brushes. Does the new regulator need to have 2 brushes to work?

RedScytheM3 wrote

Yes, I didn't eject the brush on the new regulator. The new regulator appears to only have 1 brush though, whereas the old one I pulled off my alternator has 2 brushes. Does the new regulator need to have 2 brushes to work?

No, not as long as the brush(es) are located in the same plane with the comm. If they were 180* apart then there would be a problem. If you ordered the correct PN as above then you should be fine.

RedScytheM3 wrote

Yes, I didn't eject the brush on the new regulator. The new regulator appears to only have 1 brush though, whereas the old one I pulled off my alternator has 2 brushes. Does the new regulator need to have 2 brushes to work?

Did it end up doing the job? Thinking about doing this instead of my whole alternator.

MRAT3D wrote

RedScytheM3 wrote

Yes, I didn't eject the brush on the new regulator. The new regulator appears to only have 1 brush though, whereas the old one I pulled off my alternator has 2 brushes. Does the new regulator need to have 2 brushes to work?

Did it end up doing the job? Thinking about doing this instead of my whole alternator.

It did not work. I initially thought I installed the wrong regulator, but in reality I installed the correct one and installed it correctly. The problem turned out to be a cracked bearing housing in the alternator. I had to replace the whole thing. It sucks I did double work, but at least I was able to sell the regulator and get the money for it back. If I could go back I would just have replaced the whole alternator unit since it comes with a new regulator attached anyway. The alternator at that point had done about 100k miles so it was time to be replaced.

I have an an alternator off of a 2008 e92 m3. Everything works on it when I took it off. Has about 100k miles on it. I would part with it for super cheap bc its just sitting in my garage now. I swapped mine out along with pulleys, valve cover seals etc... pm me if interested.

RedScytheM3 wrote

MRAT3D wrote

RedScytheM3 wrote

Yes, I didn't eject the brush on the new regulator. The new regulator appears to only have 1 brush though, whereas the old one I pulled off my alternator has 2 brushes. Does the new regulator need to have 2 brushes to work?

Did it end up doing the job? Thinking about doing this instead of my whole alternator.

It did not work. I initially thought I installed the wrong regulator, but in reality I installed the correct one and installed it correctly. The problem turned out to be a cracked bearing housing in the alternator. I had to replace the whole thing. It sucks I did double work, but at least I was able to sell the regulator and get the money for it back. If I could go back I would just have replaced the whole alternator unit since it comes with a new regulator attached anyway. The alternator at that point had done about 100k miles so it was time to be replaced.

Just read this... my bad. Still have this one if anyone is interested.

Hi, I have similar trouble now.

E92 M3 2011, now w 60k miles. I have the OEM battery AGM w 90 Ah, 900A. I have no codes at diagnostic, only the car showing me "increased battery discharge". Definitely need to replace, recharging isnt help, loosing voltage very fast.

But parallel I check voltage on battery when engine is running and it shows 14,8-15V. Based on threads there I have to be around 14,5 and 15 show to much and the regulator or alternator have to be replaced. But no idea how should I kbnow what to change, if both or regulator only.

Based on BMW there can be 2 variants of alternator numbers.

12317838656 is the EOM, produced by Valeo and used by BMW during car production, I didn't find any alternative product at bimmercat.com
https://www.fcpeuro.com/Parts/?keywords=12317838656

12317837981 is also OEM and BMW recommend this one for case of warranty replace of origin one, no idea why, but dealer told me because is cheaper. For this item I found interesting alternative from Valeo directly, for 280usd instead the BMW 545usd. I believe this Valeo have to be same as the origin BMW from Valeo (looks similar situation as w throttle actuator from Siemens VDO which is -40% cheaper as BMW OEM, which is produced by VDO, you pay 40% more only because BMW label on it, that all. So w this alternator it have to be similar.)
https://www.fcpeuro.com/Parts/?keywords=12317837981

Do you have any experience w that? Or which alternator you recommend?

Regarding regulator 12317847517, look like there isnt any replacement at bimmercat.com but at threads there is recommended the second bellow Bosch
https://www.fcpeuro.com/Parts/?keywords=12317847517
https://www.ecstuning.com/b-bosch-parts/voltage-regulator/12317561939~bos/

I am the original poster that started this thread. I ended up replacing the entire alternator which has a new voltage regulator.

The codes would still sometimes pop up. I replaced the battery and they never came back.