Front windows do all they should from the driver and passenger side door switches------except the passenger window won't go down when the driver side switch should be telling it to. Goes back up and does both from the passenger door switch.

Am I right in thinking fault should be in the driverside switch or loom between it and the comfort/convenience module or could it be in the driverside window electronic box?

Think it must be the switch itself; 'cos the same wire is used for up and down (a different resistance is connected between it and ground to tell the door control module which way you've chosen), so can't really be the wire that's the problem.

Try disconnect both looms both sides see if it works if it does prob driver motor as that’s the main module for them both

New chinese switch on order before I strain the brain further. Only £7. Why do modern things have to try to be so clever. One wire for up and another for down was fine when the world was in black and white.

If the new switch doesn't sort it then I will have to look at the driverside window module. Doesn't the convenience unit play any part in window operation?

Both front door modules have CAN connections with the Onboard Supply Control Unit (under relay panel). Presumably this is how the drivers side module knows what is being commanded by the passenger side switch, and vice-versa. Wiring from the switches seems to only go to the door module on their own side of the car.

If the driver's side window goes up and down with the passenger side switch, then the driver's side door module seems capable of doing its job, when given appropriate commands; I think that also rules out trouble with the CAN connections and Onboard Supply Control Unit.

 

New switch finally arrived. Sorted. Interestingly the insides of the old one are just like a TV remote. No mechanical parts. Just a circuit board and silicon overlay carrying 'carbon' contacts which short the various contacts. Couldnt find a fault but a clean of each shorting button would probably work. However it's in the bin.

One usefull thing I did whilst waiting for the switch to arrive was to locate and clean underbonnet earthing points. I found four bigish ones, three on the passengerside inner wing and one on the driverside.

Last scan full autoscan found no faults at all. Unusual for this car!

9 hours ago, LB123 said:

Couldnt find a fault but a clean of each shorting button would probably work. However it's in the bin.

 

 

Cleaning didn't work on mine but a new switch did. I think the conductive pads on the buttons eventually fail. There are lots of YouTube videos about TV and other remotes doing the same thing and being 'repaired' with anything from bits of glued on foil to conductive paint. You can even buy conductive pads on ebay but I don't think they would last long.