Hello All,
Couple of months ago I picked up an 86 XJ6 for a daily driver. I've been working through all the little issues that come with a car that had been sitting for a few years.
One of the first things I tracked down was why the windows weren't opening. After going through all of the usual suspects, I went to the black Load relay. Sure enough, it was bad so I did a quick swap and that's been good for about a month.
Got in it yesterday and the windows wouldn't go down... So I started through it all again. Master switch, good... Thermal breakers, good... Load relay, testing good off the car. So I swapped the load relay just in case.. Still nothing.. Checked the power feed from the battery (brown wire), good... Checked the ignition feed power wire (pink/white), nothing.. AhHa, there's the problem...
S57 doesn't show any of the fuses being for the window motors, but checked the fuses anyway... all good...
So with some other things going on, I thought the electrical part of the ignition switch could be the problem.. but wasn't going to take that on on a Sunday morning..
Just as a matter of checking, I bridged the relay terminals from the battery power and ignition power with a screwdriver... Got the "click" from the relay, and windows started working...
Knowing that was just a temporary test, I buttoned everything back up and figured I'd look at it later...
BUT, after that bridging, now the windows are working again (without anything being altered)...
I'm just going to have to let it roll, and see if they act up again...
Cheers,
David
(shop.EverydayXJ.com)

 

Corrosion on some connection? Relay points need burnishing? Lucas gremlins.

 

the 1986 and 1987 XJ are a little different electrically from 1985 and older XJ, with different a/c system and different door locking system and who knows what else.
Doug knows how different.

​​​​​​I would replace the Windows & Sunroof Master On-Off switch and check the wiring to it. It could be intermittently failing.

 

David,
The window lift relay with the brown battery feed and white/pink strip wiring should go to fuse #11, i can email you an extract in colour of the window circuit if you want.