The car we're talking about here is a 1989 XJ40 Jaguar Sovereign 3.6(the middle model) RHD.
Basically my problem is when I turn my windscreen wipers on they don't stop, that is even after the car is turned off.
The first time that this happened, was one morning, to clear the dew on the windscreen I turned the wipers on (as you do) and when I went to turn them off they kept going. As my schedule is fairly tight I kept going, turning the wipers on and off several times without success. At about the 10-15 minute mark of the journey the wipers went to intermittent (as they would if you turned them on that way) at which point I turned the wipers on and turned them off and they stopped. No problems from here but I didn't need the wipers again.
The second time it happened it was raining fairly steadily and I had the wipers on for the entire 25 minute trip. When I pulled up and turned the wipers off they kept going, I turned the car off and they kept going. I restarted the car and turned the wipers on and off and they stopped. From that point on I had no trouble with the wipers that journey, restarting and stopping them several times.
From that point on if I've come across a shower of rain or the wipers have accidentally been turned on I have unplugged the wiper motor when the wipers are no longer needed. Usually but not always the wipers remain off at the completion of the trip when replugged. Just unplugging and replugging makes no difference, they will just keep going.
While it doesn't rain here that often, and I have another XJ40 for when it is raining, this situation is still a little annoying.
I'm guessing the problem is to do with the wiper module in amongst the relays and CPU's under the passenger side cover but I thought I would check in case someone had had the same problem and it was something else for example the wiper motor itself or some hidden fuse. If it is the module, how important is it that the DBC number matches as there are several on eBay that all have different numbers and the one I pulled out of the 1988 Daimler out the back is different again (than the ones on eBay)?
Any help would be appreciated

 

This is really strange to me because when you turn off the engine the wipers are supposed to sleep as well .
My recommendation is pull the stalk down once and release your hand , just once and see if it stops and do this with the engine is running .
You should be able to see 1 indicating down postion as well

 

The wiper will NOT stop until it is PARKED or the fuse under the glove cubby is removed.
The plastic park cam in the wiper motor box is loose OR the micro-switch has failed. I keep micro-switches in stock for my XJ40.

I also installed a 15 amp fuse in the RED/SLATE power wire next to the wiper motor so I can pull it when the wiper motor keeps running. (it's in series with the 7.5amp fuse under the glove cubby)

It is a pretty common fault.

bob gauff

 

Yes the problem is a bit strange .. and the wipers most certainly don't go to sleep when the power is turned off. I've tryed doing all sorts of things with the stalk as well short of ripping it out and throwing it away.

Thanks for the ideas Bob, I will investigate further.

 

My wife took my car out the other day and said that she had this problem when she went to wash the wind screen. Even when she took the keys out of the ignition it kept going.
Would the fuse trick work for me too?

 

The 'PARK SWITCH' in the wiper motor assy stops the motor in the correct position. If it fails, it will keep the wiper motor running until it PARKS (IT NEVER WILL!!!!!!!!!!)

The plastic cam SOMETIMES breaks and keeps the switch 'GUESSING' at the correct stop point, but only taking the cover off and diagnosing will tell what part has failed.

Switch is MOST common but take it apart and stop guessing.

bob gauff

 

Thanks to the Motorcarman the problem is all fixed . I replaced the Omron V-16-1C24 switch on the wiper motor and it's all good as new.

 

Good to see , thanks for your feedback I appreicate that
Happy wiping lol