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Old 11-17-2021, 11:22 AM
JP-X3 JP-X3 is offline
Join Date: Jan 2011
Location: Houston, TX
Posts: 24
JP-X3 is on a distinguished road
Water can get into the cargo area due to clogged sunroof drains. This happened to be back in January 2021 and caused the transfer case to go into failsafe mode (permanent 4wd, hard to steer) and of course the trifecta of ABS, brake and 4x4 lights were all lit.

It took me a while to diagnose this issue because I had recently replaced the transfer case actuator, some front suspension arms, got an alignment and replaced one rear wheel bearing so I was always suspicious about these repairs causing other problems, I was wrong...

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. Drove the X3 on 2WD for 4 months. I bought the BMW 1.4 scan tool and was not able to diagnose the culprit. Finally I downloaded INPA and got a cable from Ebay. This software has an actuator and VTG ECU test function, there was no communication with the ECU so I bought an used one from Ebay for $50, replaced it and voila! it works again.
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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