1992 XJ40 Window Problem - new member

Hi All,

I’m a new member here from London, having just purchased a 1992 4.0 XJ40 Sovereign. The car has been generally well looked after and is in decent condition and runs well, but with a few electrical issues that I am starting to look into.

I have an issue with the passenger side front window. It has lowered from the driver’s side switch but will not raise using that switch. On the passenger door itself, the window will neither raise nor lower. So currently the window is lowered and won’t raise.

I have looked at a number of posts on different sites as I know window problems are not uncommon on XJ40s. So far I have replaced the switch packs on both the front doors and the problem remains the same, leading me to assume the switches themselves were fine.

I have also removed the Fuse box in the passenger foot well (Fuse 2) and re-soldered the joints, as I understand this is also a potential weak point. Again, nothing has changed.

If anyone has experienced the same issue or has any suggestions, I would be very grateful for any help you could provide.

Many thanks

First thing you need to do is remove the door panel and direct feed power to the motor to get the window up, if that doesn’t work then you will need a replacement motor.
If that is a success then it is back to the switches, they are interesting as they have two pole relays and the power goes through the ‘back’ of one to power the other sometimes it’s just a case of giving the relay points a clean.
Do NOT be fooled by ‘ohming’ the switches, they can ohm out ok but they fail to carry the amps that the motor requires.

1 Like

I would check glass runner seal first prior to moor replacement. Use to have the same issue in XJS. After replacing rubber runner - like new, smooth and constant. If felt is rubbed on the inside of the channel - rubber below will catch it/prevent slide. You can pull the runner out, measure and order universal runner which will be slightly wider and slightly less noise-insulating.

My initial feeling is still with the motor, OP needs to make sure it’s actually working before going any further. BTDT

Many thanks for the replies.

I will take the inside of the door apart again and investigate further. As the window came down from the driver’s switch only I initially assumed the switches might be the issue rather than the motor, but as I can’t manage to raise the window from either switch, even after having replaced them both, I will take a look at the motor itself and the seal as well whilst I have it apart.

The motor is fed +/- and -/+ from memory to facilitate the up and down motion.

Yes, as you mentioned that’s first right thing to do… Motor replacement would be the last option…

Thanks very much for the advice above. I finally had a chance to take the door apart again yesterday.

By reversing the connections on the motor, I was able to raise the window using the down switch on the driver’s door, suggesting that the motor itself is good as it will operate in both directions.

The window also ran smoothly and isn’t sticking anywhere.

This would lead me to believe there is a problem with the switches but I have already replaced them on both sides and the result was exactly the same - no movement on the passenger side and down-only on the driver side.

The replacements were used items but it seems unlikely that all the switch units would be faulty in exactly the same way.

I’m just wondering if there is anything else I should be thinking about?

You can strip the switches down and clean the contacts in the relays, its a bit fiddly but doable, each relay has two contacts so you need to clean both of them.

Isn’t there an ‘isolation’ switch on the driver door panel which has some effect on the other doors window operation? Isn’t that switch a ‘child proof’ feature?

I think that just isolates the rears Bryan.

Robin,

I specifically checked that and in my wiring diagrams for that year the passenger front door window as well as both rear door windows are wired so that their respective up/down switches are connected to the isolation switch in the driver door switch pack. [Yellow/white wire from each to pin 20 of the 24-way yellow connector at the driver’s switch pack]
Perhaps they figured children (or adults who mess with things!) could also occupy the front passenger seat. :slight_smile:

Thanks for the replies. I’ll take another look. I assumed the isolation switch was for the rears only, so will look at that.

Nick,

According to the wiring diagrams, that is true from '93 MY onwards.

Jaguar must have had a change of heart and changed it from the earlier models to stop front seat passengers from complaining! :slight_smile:

Are the rear windows working? If so that would seem to rule out the isolation switch. Have you checked the integrity of the ‘up’ wire from the switch to the motor?

I should have known :joy::joy: