Drive unit noise - My15 Rex 54k

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Sep 20, 2019
Hey all,

Troubleshooting my GFs I3, MY15 with 54k on the clock. Over the last 5k miles the drive unit has been progressively getting louder. No unusual noises aside from the typical electric sound until last week where the car ended up "not going into gear" with a drivetrain malfunction message displayed on the IC. Advised my GF to lock the car and step away for a few minutes at which point the car went into gear and she limped it home. The drive unit now makes a distinct bad bearing sound when moving, it seems to be louder at low speed and gets smoother with speed.

I pulled the codes using a generic reader and got p1e90,p1e91,p0a42,p0a40,p0a3f, which indicate drive motor position issues, low and high circuit along with some inverter over voltage issues. Got ISTA installed and made myself an ENET cable so I will run through the proper diagnostic in the next day or two.

I searched around and it seems there are a few reports on drive unit failures which were mostly handled by the dealer by replacing the whole unit; It seems a new drive unit is around 4kUSD, ~2kUSD for a used one. I would like to explore the feasibility of doing this myself and have some questions:

* Has anybody explored the idea of rebuilding the drive unit? It seems the drive unit is specific to the I3/I8 line and is referred by BMW as a HSM, Is there any mention who the OEM manufacturer is? Are there any companies rebuilding these motors? Are there any OEM manuals for these motors, workshop service manuals etc?
* Has anybody opened these? What does it take? Do you need a press jig or any other specific equipment? The drive unit seems to be an all in one unit, with transmission/diff included as part of an assembly, is the position sensor located on the transfer case output or internally prior to the differential unit?
* I reviewed the procedures in ISTA and feel fairly confident that I can accomplish this in my garage with a lift. There are a few special tools listed that seem to be used in addition to a lift table in order to support the unit as it is being removed. The special tools are relatively affordable at 30$/piece from ECS. I have a hydraulic lift table and could rig something up to support the assembly. Alternatively I have made drivetrain cradles for my other cars previously out of some square tubing and threaded rod. How feasible is the removal of the drive unit by a hobbyist/diyer?

My next order of business is to pull the trunk cap and use a stethoscope to locate the source of the noise and to run through the diagnostics procedures in ISTA. Any other suggestions or similar experiences?

Thanks all
I did ISTA diagnostics, the following things were of note(below). I ran the test plan for the Inverter and EME internal fault but nothing really came up although I got some decent reading material from it. The position sensor is internal to the assembly and not on the output shaft side, meaning the case would have to be split, which probably means more special tools. Sounds like I will be dropping the drivetrain down.

2228B8 Emergency manager information, EDME: Unable to activate driving
90637 No Information
222890 Emergency manager information, electrical machine: No internal
90637 unknown Information
22286D Information emergency operation manager: Electrical machine
90637 No Information
222869 Information emergency operation manager: Electrical machine
90637 unknown Information
222626 EME: Internal fault (active short circuit requested) 90637 No Information
222316 Inverter: Wrong sum current 90637 unknown
22202A Electrical machine, rotor position sensor, signal: Amplitudes too great 90637 No
222029 Electrical machine, rotor position sensor, signal: implausible,
excessive deviation between sine and cosine signal
90637 No
222021 Electrical machine, rotor position sensor, signal: Not plausible 90637 No
222015 Electrical machine, rotor position sensor, signal: Faulty speed 90637 No
222014 Electrical machine, rotor position sensor, signal: Faulty motor position
90637 No
21E96F Driving readiness information: cannot be established after driver's
driving readiness request
90637 No
Good luck man. Keep a video or picture journal of your work and progress. It would be interesting to see how it's done and what it takes to do it!
I've been on this board since 2015 and a non-dealer EME repair is something that I've not read about before.

Seconding Arm's comment... it would be great to hear how you solved this problem.
Certainly worth an email - to see if they recognise the codes? ;)
Email: [email protected]

The EME from new will be horrendously expensive.

That's even assuming it's the EME? There's also the inverter REME?

I've followed Shaun Dobbie on YouTube for a while - so he's done a few odd repairs over the years plus numerous trips to the main dealer. Not necessarily an answer to your fix - but interesting all the same.
Here is how this sounds, the drive unit is coming out soon.
zlykot said:
Here is how this sounds, the drive unit is coming out soon.

When I look at that video it sure seems like the i3 is stationary.

The sound in your video sounds rotational. As the i3 in your video appears to be not moving, I suspect a problem with either the air-conditioning or battery cooling systems.
This is with the car being driven at low speed/load, noise only happens when the car is rolling and is speed dependent. Happens in Drive, Reverse or Neutral. I initially suspected rotor/pad/bearing issue but the noise is not coming from that location. I also fired up the Rex in emissions test mode and Rex runs smooth with no issues.

Im leaning towards it being the etrans/diff, which to my surprise is rather affordable (500$ or so from the dealer with CCA discount). However, It is a relatively labor intensive procedure to swap it out as the drivetrain has to come out.

The car was involved in a small accident, where the rear quarter was hit. It's most likely related to it, I will let the insurance company inspect it and evaluate my options after that.
The interval of the noise pulses is relatively infrequent which tends to suggest it's happening at or after EME gear reduction, so yes, it could turn out to be with the "trans/diff"!
If there is noise it is mechanical, shouldn't be the EME. It could be the infamous motor bearing in pre-facelift models.
The interval of the noise pulses is relatively infrequent which tends to suggest it's happening at or after EME gear reduction, so yes, it could turn out to be with the "trans/diff"!
It has been almost 2 years now since you posted the noise. Can you tell us what it was and what was replaced?