'04 XJ VDP (x350):

On the long drive home from my sister's wedding yesterday (all of it in the rain) my wipers started acting up. Everything was fine when about midway through the drive I stopped to get some coffee and a bathroom break. 5 mins later, I get back in the car, and as soon as I turn it on, I notice the windshield wipers are pausing in the middle of their sweep/stroke, instead of at the bottom of the windscreen as usual. More specifically, when they are in intermittent mode (or auto, if the auto-speed is not continuous), they function as normally (sweep, then pause for a moment depending on the delay setting or the auto-determined setting, then another sweep) EXCEPT that instead of pausing at the bottom of the windshield like usual, they are pausing in the middle of the screen. They will then swipe up to the normal extent of their sweep, swipe down to the bottom of the windshield, then up halfways and pause at the same spot again. Similarly, if I turn the wipers to OFF, they 'park' at that same position in the middle of the windshield, not at the bottom edge as usual. If I have the wipers set in any of the 'continuous' modes they work perfectly normal. It is only when they are supposed to stop/pause that they do so in the wrong place. If it matters, I pretty much always keep my wipers in the auto setting, and they were in the auto setting when this first occurred.

As far as trouble shooting goes, I have bench-tested both of the wiper relays (R4 and R8) and both work perfectly so far as I can tell (with no power applied, posts 3 & 4 are connected; with power supplied to posts 1 & 2, posts 3 & 5 are connected). Both their coils shows a reasonable resistance (~90 ohm). If I swap them with each other or any other of the 2 position relays, the wipers still act incorrectly. With the wipers running, and a finger placed on the 2 relays, I can feel/hear relay R4 cycling/clicking every time the wiper pauses in the middle of the windshield and again when it starts moving again. To me it seems like the error is not in the relay system, but in whatever sensor/mechanism/device controls the relays. I am not sure how the wiper system works (no schematics/diagrams) so I do not know where to go next... is there a position sensor that might have gotten indexed incorrectly somehow (thinks wipers are at the bottom edge when really they are midway through a stroke, etc), or is this function integrated into the wiper motor itself? Any help is appreciated. Thanks guys!

 

I think the wiper problem is the park switch. Answer in this months 'jaguar enthusiast' to a similar problem.....
"when the system is in intermittent wipe or auto wipe, the motor is powered for a short pulse just to move the motor from the park position. It is then the job of the park switch to complete the wipe by taking the motor back to its park point. If the switch is stuck in the park position then the wiper pulse will start the wiper then stop halfway up the screen, as it still feels that it is in the park position."

It does say you should check the earth on the inner wing under the motor first. All so says to replace the switch you need to change the whole motor

 

Thanks for the quick reply! My problem sounds a little different though: it never parks at the bottom, it seems its 'park' spot has relocated to the middle of the windshield. Like if i have it set to a slow intermittent (long pause) it will pause for the whole time at the middle of the windshield, then go up and down (not pausing at all at the bottom position) and return to the middle position where it will pause again for a full pause. Similarly, if I turn the wipers off completely, they don't park at the bottom (or at whatever position they are in when I turn them off, as I would expect if the park switch was stuck in the park poistion), they go until they are at the exact same spot in the middle of the windshield and stop there. Maybe I'm just reading the above quote incorrectly, but it sounds like with the situation described (bad park switch), it will park as normal, but will get stuck halfway up? Either way, gives me another thing to check. Any information on which wire/terminal is ground (earth) coming off the motor? I've only had the car for about a year and havent done much work on it, and dont have any schematics/diagrams/service manuals for it, so kinda in the dark as far as whats what

Hoping I dont have to replace the entire motor

 

I am not sure, but I think the wipers ignore the park switch for the duration of the 'pulse' and only when this is finished does it check with the switch, which if stuck seems to end up with the wipers parking in the middle of the screen!

You can get helpful docs here
JagRepair.com - Jaguar Repair Information Resource

Hope you find the doc you need!

Peter

 

The outrageous thing is that for the sake of supplying a $15 switch, Jaguar insist on selling the whole wiper motor and mechanism. This is not a cheap part.

No doubt somebody will find out where this little switch comes from and supply it separately, but so far nobody has stepped up to the plate for us. We need a Bagpipingandy Mark 2 !!