Z4 E89 Driver Window Switches Issue

[Neverlast]

Hi,

Im having an issue with a Z4 E89 driver side window switches.

They were working fine but since one of the plastic buttons was
broken it was taken out and replaced by an aftermarket part.

The aftermarket part did not work at all, none of the controls responded
so I put back the original part. Now the original part only partially works,
the window buttons do not respond, only the side mirrors motor does
what it is supposed to.

The unit gets power as the buttons light up. The passenger switch
works and when using the remote or roof buttons in the car windows
operate as they should.

I scanned the codes with Bimmerlink and one code persists:
9CBA Communication with LIN keypad interfered.

Also tried opening and cleaning the master switch with a little IPA
and found everything to look clean and no visible burning marks.

Is it possible that the aftermarket unit cause some issues or is it just
bad luck and timing and there is now a short in the wiring somewhere?

All fuses corresponding to windows were also checked and all seem fine.

Any input and help would be greatly appreciated!

[B21]

Unfortunately I suspect only swapping it with a known good one will allow you to determine the fault..

[Neverlast]

Well, to come back and report my findings so far:

After clearing the errors the unit still did not respond but after the car
has been left overnight and just when I was ready to tear into the door panel
and wiring buttons started to work.

It was either afraid of my electrical skills or the FEM finally started
to communicate properly with the master switch. Hopefully this is the case
and I will be saved from combing through many wires. If anything
new occurs will report.

[B21]

Originally Posted by Neverlast

Well, to come back and report my findings so far:

After clearing the errors the unit still did not respond but after the car
has been left overnight and just when I was ready to tear into the door panel
and wiring buttons started to work.

It was either afraid of my electrical skills or the FEM finally started
to communicate properly with the master switch. Hopefully this is the case
and I will be saved from combing through many wires. If anything
new occurs will report.

If they get damp they can go offline for a few days till they dry out

[Neverlast]

Well the saga continues...just today the drivers window buttons stopped working
again, no obvious reason, the car was just sitting for a few days in the garage
so I doubt it has anything to do with moisture as I cleaned the board when I dismantled it
and the car was never exposed to any rain, nor were there any spills on the controls.
If anyone cares to join with any new ideas please, by all means!

[B21]

Looks like it’s just gone south..

[Neverlast]

To whom it may concern in the future:
my issue was a faulty master control switch.

The new part came in today and after replacement
everything seems to be working as usual.

Just out of curiosity I took off the big capacitors from the
old board and they were all in spec, so it must be some
other SMD parts which I cannot diagnose or replace myself.

[B21]

Originally Posted by Neverlast

To whom it may concern in the future:
my issue was a faulty master control switch.

The new part came in today and after replacement
everything seems to be working as usual.

Just out of curiosity I took off the big capacitors from the
old board and they were all in spec, so it must be some
other SMD parts which I cannot diagnose or replace myself.

Thnx for the update…pretty common for a new unit to work with no obvious reason for the old unit to fail..