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2007 335i E93 code 9cba window switch

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Nelson
 Nelson

After some water intrusion i got , the lin bus is disrupted at the driver door window switch. I replaced the switch but code remains so my guess is another lin slave is ruining the bus, what are the most likely offenders?
Currently unplugged:
Driver door window switch, exterior mirror, underlight, speakers.
Passenger door window switch, exterior mirror, underlight.
Domelight, headlight switch.
Lin bus is currently reading 8.8 volts (at driver window switch) but jumps to 9 whenever i press a button on it. With driver door switch unplugged its at 9.5 but jumps to 10 sometimes.
2007 335i E93 Auto US spec

Quote
Topic starter Posted : 05/01/2025 2:31 pm
Serge - UpFix Team
 Serge - UpFix Team
Famed Member Moderator
  1. First suspect is wiring harness - could be wiring corrosion present on the harness going to the JBE module. If 12v isn't stable or reaching the JBE that could be it. The LIN-wire (brown or brown/white) could also be at fault.
  2. Door window switch or mirror - connect and disconnect the switch and/or mirror, and see if the code/issues change. If they do these parts could also be at fault.
  3. The JBE (gateway module) has corrosion - inspect this module closely for any signs of corrosion
  4. FRM (footwell module) - This directly interfaces with the JBE and is also prone to corrosion. It's best to scan the FRM with a BMW-specific OBDII scan tool. Check the kick panel area and under the carpet, driver's side, for any dampness.
Another less likely culprit is something that failed during an aftermarket head unit installation. If there is an aftermarket head unit, this might cause the DTC 9CBA. Wiring to JBE, JBE itself, and the FRM are top suspects.
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Posted : 05/01/2025 2:33 pm
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