P38A Passenger electric window not working

Montyjohn · Sep 6, 2023

I'm about to start diagnosing why my passenger electric window isn't working.
I figure it's either the wiring, center switch pack, motor or the computer box thing behind the door card.
To save me some time, does anyone have some tips, or order to check things in.

I assume the switches are all CAN operated so no idea how to test them, so my plan was to.

Multimeter on the motor. If getting power then then swap motor, otherwise,
Swap computer thing with the drivers side (means removing both door panels which will be a bit of a faff) (note, all other door stuff works, so might be a waste of time), if no change then
try cleaning up the contacts on the switches, if no change then,
urrr, maybe try a second hand switch panel (eBay £80, spending money now, don't like spending money) , if no change then
rip out all the wiring and check all connections and joints, if no change then,
Passengers don't need windows that can open.

Anything obvious I'm missing, suggestions on what to check in what order etc?

Datatek · Sep 6, 2023

Montyjohn said:
I'm about to start diagnosing why my passenger electric window isn't working.
I figure it's either the wiring, center switch pack, motor or the computer box thing behind the door card.
To save me some time, does anyone have some tips, or order to check things in.

I assume the switches are all CAN operated so no idea how to test them, so my plan was to.

Multimeter on the motor. If getting power then then swap motor, otherwise,
Swap computer thing with the drivers side (means removing both door panels which will be a bit of a faff) (note, all other door stuff works, so might be a waste of time), if no change then
try cleaning up the contacts on the switches, if no change then,
urrr, maybe try a second hand switch panel (eBay £80, spending money now, don't like spending money) , if no change then
rip out all the wiring and check all connections and joints, if no change then,
Passengers don't need windows that can open.

Anything obvious I'm missing, suggestions on what to check in what order etc?

No CAN bus on the P38. does the window not go up or down?
The usual problem is the switches in the centre switch pack, the contacts corrode. Easy enough to fix, the switches can be taken apart and the contact points cleaned, just done 2 switches on one of mine. You are unlikely to need a replacement switch panel.
The next possibility is a broken wire between the A post and the door.
Could also be the outstation, you can check by swapping with the one from the drivers door.

Grrrrrr · Sep 6, 2023

If you have a Nanocom you can not only trigger the window using it but also see what the BECM sees when you use the switches. The switchpack talks to the BECM and the BECM tells the window what to do, although I cannot recall if it does it direct off the power-board or via the door outstation.

pwood999 · Sep 6, 2023

+1 on using Nanocom to check the switches, and drive the window motors. It can also be the connector in the door jam.

If there's a relay failed inside the door outstation, the locks, etc can still work. Best check is the left-right swap to see if the fault moves.

mystery · Sep 8, 2023

circuit

Montyjohn · Sep 11, 2023

my window is now working.
I don't have a NanoCom and the rsw diagnostics I use doesn't work monitor windows si it was trial and error.
Luckily, the first thing I checked was the problem.
It was the switches pack (thanks DataTek for suggesting I start here).

I pulled the board out, and before removing the switch that was causing the issue, I sprayed some carb cleaner under the switch.
It now works perfectly.

Datatek · Sep 11, 2023

Montyjohn said:
my window is now working.
I don't have a NanoCom and the rsw diagnostics I use doesn't work monitor windows si it was trial and error.
Luckily, the first thing I checked was the problem.
It was the switches pack (thanks DataTek for suggesting I start here).

I pulled the board out, and before removing the switch that was causing the issue, I sprayed some carb cleaner under the switch.
It now works perfectly.

Good result, just be aware that carb cleaner can damage some plastics. Better to use Servisol contact cleaner/lubricant.

P38A Passenger electric window not working

Montyjohn

Well-Known Member

Datatek

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

pwood999

Well-Known Member

mystery

Well-Known Member

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Montyjohn

Well-Known Member

Datatek

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