https://xoutpost.com/bmw-sav-forums/...refurbish.html

Very detailed thread how to refurbish valeo Alternator.

Ok, so I finally pulled the alternator and had it tested by a certified recycler. 100% good.

Oddly, as I was pulling the alternation I noticed the connector was good and tight but the push in locking clip was missing. I have a replacement clip not a perfect fit but if I bend it a bit should work. Don’t think it’s the problem but the rebuilder said the alternator had been worked on at some point so I assume whoever reinstalled lost the clip and didn’t say anything about it…..

I’ll put it back together and see if I can get the clip to work, then move on if it’s not the problem..

Thanks.


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I'm not sure what the locking clip is there, but if you found something wrong, that is a good thing to fix, of course. Every connection to the alternator of course needs to be tight, clean, torqued properly on the plastic coated nut. Connections to the starter and jump port too. On these 3.0i's, the alt cable goes from the B+ connection on the alternator to the starter, then from the starter to the engine bay jump port, then through the jump port nut to the back side, then from there to the battery positive terminal, after making it through the pyro fuse.

But I would not put much (any?) faith in the "certified recycler" saying it is 100% good. From the beginning, your description of the problem shows it is intermittent. Sometimes present, sometimes not. If the tester checked it out when the problem was not present, they could give you a clear diagnosis that is wrong.

I agree with AndrewWynn's previous advice on this, other than that I would rate the difficulty of slip ring replacement as much harder. Andrew and I seem to be maybe the only ones on here that have done that procedure so far. I'd rate it an 8 out of 10, where 10 is brain surgery or a blindfolded transmission rebuild. Maybe not super hard to do, but it's pretty easy to fail at = mess it up by having one of those copper wires break while surgically removing the epoxy coating.

On my last refurbish I didn't change the slip rings because I just changed the polarity of the brushes instead.

Using heat to remove the epoxy drops the difficulty in half for that part but I broke the very end of the field winding off and had to patch that so it's still risky.

If you aren't well versed in wire/solder repair, stick with brush only fix. (it's not difficult to follow my direction on how to swap polarity and a couple people have reported success doing the procedure).

Ok, reinstalled the alternator, cleaned the MAF. Brake and DSC lights still on and shortly after cranking the Trans. failsafe light comes on.

Lurches into reverse, lurches into drive. Barely moves in first gear in the driveway. Making a bit of a whirring noise in gear.

CEL codes show all four O2’s not functioning dont remember the code #.

Gear lurches have me concerned. I plan on checking the tranny fluid level at the pan. (I replaced the trans filter and fluid several thousand miles ago)

Suggestions? Thanx.


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Dreaded trans. Failsafe prog.
 

Gear lurch is normal if trans failsafe. you need to clear the code from the transmission module.

You also have to confirm your alternator is on putting steady voltage. The symptoms are describing are bad alternator output.

FYI, that can happen easily if you did not tighten the nut
on the alternator. I did that once that’s how I know.

Also if the nut that secures the jumpstart post is loose you’ll get the same symptoms. Shows up about twice a year on xoutpost

Tuned in for a solution. Weird to have MAF, o2, and EGS codes and not have it be electrical (usually alternator as pointed out).

I'd say to check the mechatronics connector at the trans for corrosion or oil intrusion... but don't think that would generate MAF or o2 codes.

I was going to add about the transmission connector. That was the cause of my trans failsafe other when I forgot to tighten the nut on the alternator output. (wow did that connector get hot: it was literally glowing).

I didn't mention because trifecta comes on with no preexisting situation like wheel sensor it's almost always alternator.

Replaced ≠ fixed. I bought a refurbished and it lasted less than 3 drive cycles. Follow the symptoms even if it means reworking a part you just worked on.

Ok, thanks.
I made sure to tighten the alternator cables, will re-check the jumper cable posts.

Looks a bit deeper on my code reader and got a “failed to connect” message for EGS section. 3A is the code.

Along with 16 DME/DDE does not fulfill torque request
17 Coding error (What?)
And
10,02,01,03 No found…..

Likely going to put in an Alt later in the week. Possible the EGS switch is bad?


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Transmission connector was not dirty, but sprayed with deoxit and reconnected. No change….


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