Quote:
Originally Posted by JP-X3
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I was able to get the transfer case to 2wd by applying 12 volts into the actuator motors' cable at the transfer case controller (VTG ECU) and then disconnected it.
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I took apart the old ECU and to my surprise I found out it's not water tight so water got it, corroded everything and created a short circuit.
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I think we've now got a similar issue. To which pins did you apply + and - to get it back into 2WD? Same GND as vehicle? Pic?
Recap:
Last year (after my above post in this thread), I'd installed a rebuilt driveshaft (including new U-joints and guibo/doughnut) in our '08 X3 3.0si M-Sport due to one U-joint that was developing some slop (not easily user replaceable on my original due to tack welds, although seems to be user-replaceable on the rebuild due to circlips), and that also cured the rumbling. I eventually cleared the dash light triad with ISTA (due to trouble deciphering online translations of our half-english/half-german version of INPA). So we had properly working AWD/4WD last winter.
This summer, the light triad returned with 55c4 as the only code, which I actually suspect is due to a funky speed sensor that I have yet to replace. I'd read somewhere that the same code can be caused by faulty DSC control unit, bad Steering Angle Sensor, and/or failing Speed Sensor. We had noticed occasional momentary dropouts of the speedometer speed for no apparent reason, so that's why I tend to suspect the speed sensor.
Fast-forward to this past week: I was driving home one evening and encountered an epic deluge, including deep standing water (ranging from inches to over a foot) at highway speeds, which did result in some hydroplaning on the half-tread 19" summer tires so I'm sure the AWD kicked in. Although many cars got stuck, and some even kissed each other, the X3 made it home safely (and externally unscathed, albeit considerably cleaner).
But as soon as I exited the highway, I noticed shuddering from the inside rear wheel at every slow-speed turn. That is, the left rear shudders on left turns and the right rear shudders on right turns. This led me to conclude that the transfer case is stuck in 4wd.
I let everything dry overnight, but same issue the next day. Took it for a highway drive in clear weather, but no change. Removed actuator plug and blew out with air, but no change. Then dug out my BMW cable, scanned and found codes 55c4, 55c8 and 55c9. According to the mileage snapshots of code occurance, the 55c8 and 55c9 first occured during the deluge drive home, although all three codes now appear immediately after I clear codes and then restart (without even shifting out of Park). I suspect water got into something, but not sure if the VTG, wiring, or actuator itself just yet.
EDIT: The only other post-deluge issue that I noticed is that the exhaust ground strap got torn off. I doubt if that affects anything other than the post-cat O2 sensor, so it's lower on my repair list.