Problem with window

[DougX]

After SORN'ing my XK8 convertible since the end of August 2019, I put it back on the road (with 1 months tax) to get it serviced and MOT in May this year. For the month I just undertook 90 miles but I am sure never put the roof down. I have taxed it again on 1st September with the intention to attend a Jaguar gathering on 20th and to have the leather refurbished, I took it out on 1st September and put the roof down. When I went to raise the roof, the passenger window started to come down to about half way then stopped. Using the window control on the drivers door, I was able to retract the window with no further issues. However, thinking I had a problem, I lowered and raised the roof a couple more times and each time the window would go down to about half way or would jerk down two or three times, but never fully return to the door aperture. Again, using both drivers and passenger window buttons, no issues were detected. The window goes up and down properly. I had no issues with the drivers door window. I drove the car the following day and tried the same process again. No issues. Worked perfectly for now. Has anyone had similar issues? Is it due to lack of use do you think?

[mike020150]

Hi Doug,
If I'm interpreting your story correctly, it's slightly puzzling that the roof operated correctly with the window only half open. Or, did the roof stop when the window stopped half open and then, you had to open the window fully using the door button before the roof would complete the opening sequence? If it's the latter, I'd go with your suggestion of lack of use and a sticky window guide. Mike.

[DougX]

Hi Mike, the roof operation did not stop, just that the window didn’t fully open when closing the roof. The window should come down fully during the operation then close when roof is closed.

[Astromorg]

When the windows are operated from the switch panels in the door, the necessary 'message' is sent directly though a hard wired circuit from the switch panel to the relevant door module, but when the roof is operated the 'message' to the door modules is sent via the Standard Corporate Protocol network (the SCP) from either the Body Processor Module and/or the Security and Locking Control Module (I don't know which)
As the window operates correctly from its switch panel, I would think that the mechanism is less likely to be the cause, so, as the driver's side works, I would be inclined to start with passenger Door Module as an easier option, rather than with the BPM or the SLCP. First thing to check would be the connections for corrosion and a proper fit. If no joy I would swap the driver and passenger door modules to see if the problem moved with that exchange as it would if the module was fault. There's an excellent guide on how to do this in the Modern XK section of this month's JEC Magazine.
If still no progress, some deeper thought and diagnostics might be required

[DougX]

Thanks Astromorg. I did see the article in this months magazine, although it only arrive Thursday!! I will give it a try.