Wiper Parking Problems
Assuming there has been no recent work on the wiper components of your 90/110, then most windscreen wiper parking problems will normally be due to a faulty park switch. This switch is available separately from the motor and costs about £15.00 (LR part number: 520160 parking switch wiper motor series 3 & 90/110).
Though not the cause of my wiper problems, the second, third and fourth pictures below show the park switch on the gear head of the wiper motor and indicate how it can easily be changed. I would probably attempt to dismantle, clean and lubricate the old switch first though before buying a new one!
My problem occurred immediately after changing the wiper motor - the initial sweep of the wipers was in the wrong direction. On my RHD vehicle the wiper arms were now initially sweeping clockwise, hitting the bottom of the screen, twisting the wiper arms on the wheel box splines and parking in the upright position.
If you have changed the motor or wheel boxes I would suggest trying the wipers with the blades lifted away from the screen to ensure everything is working correctly. If it's not then my solution below may be of assistance.
Infact if fitting a wiper motor now I would probably check to see that the parking components in the new motor look to be in the same position as in the old one.
On discovering the problem I removed the new wiper motor from the vehicle to have
a closer look. With the gear head cover plate removed you can see that in the parked
position the arm which engages with the wiper rack cable is fully extended, so when
the worm wheel turns the initial movement will be to pull the cable.
I needed to remove the worm wheel and look at the park switch arrangement behind to
see how it was working.
The worm wheel runs on a shaft which extends through the wiper gear head and is held
in position by a spring clip on the park switch side.
Wearing suitable eye protection the spring clip is removed with a small screw driver,
then the worm wheel shaft gently drifted out of the gear head.
With the worm wheel removed you can see how the park switch clips into the gear
head of the wiper motor. The parking position is controlled by a plunger
which engages with a ramp on the inside of the worm-wheel.
With the worm wheel assembly in it's parked position you can see the park switch ramp.
Viewed from above you can see that the only adjustment available is to move the ramp
180 degrees to the other side of the worm wheel - the setting dictates whether the
first movement of the wipers from parked is either a push or pull and
hence whether the wiper arms initial movement is either clockwise or
anticlockwise.
Ramp in it's new position.
New position viewed from the side.
The wiper motor was connected to the multiplug in the vehicle and very carefully switched
on to test the new park position. As you can now see the arm which engages with the wiper
rack cable is now fully retracted, so when the worm wheel turns the initial movement will
be to push the cable, reversing the initial rotation of the wipers.
All back together again.
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