My Defender is a 1999/2000 model. So basically it is the 300Tdi with an ecu and new engine thrown in it. Land Rover rebuilt the dashboard not long after my car was made and it seems rewired it. I however, have the “awkward middle child” variant of the car.
The rear wiper was beginning to die before the car went in for the chassis swap. It would take a full ten seconds to move across the glass. Now I have the car back, I thought I’d replace the motor as it finally died.
Fitting a new motor is simply a case of taking off the grab handle on the rear door, removing the door skin and then undoing a few bolts. One on the bracket, the bolt holding the wiper arm to the spindle and the one holding the spindle on the door from the outside.
The motor has two connections. One for power and earth and the other for the clever wiper park switch.
The switch on the dash provides power to the Red/Green wire and basically turns the motor on and off. I was getting no joy even with the new motor. I checked everything and discovered the earth to both connectors was duff due to this little bullet connector behind the speaker in the rear nearside corner. A bit of sandpaper and the connector worked perfectly and my wiper swung back into life. It would not however, park.
The electrics to handle the parking mechanism are clever but flawed. Let me explain.
You turn the switch on and the Red/Green wire delivers power from the switch to the motor at the back of the car. When you turn the switch off, the switch instead connects the Brown/Green wire to the Red/Green wire out to the motor. This wire comes from the park switch on the motor (obviously at the back of the car). The park switch gets power from the green wire and sends it out to the Brown/Green wire only when the wiper blade is NOT parked. As soon as the blade is parked, the connection between the incoming green wire and outgoing Brown/Green wire is cut. This is a lot easier to follow with the aid of the diagram above.
The problem here is that the power is delivered back to the switch on the dash (via the Brown/Green wire) before it returns back out to the motor. In my case, this wire is broken SOMEWHERE in the chassis. I need a different solution than rewiring the car.
All we really need is to link the Brown/Green wire out of the park switch to the motor Red/Green connector but only when the wiper is switched off. I have an idea….
By using a relay, we get the same result without the need for power to go all the way back to the dash switch. In fact, the complex rotary switch can be simplified into an on/off for the rear wiper and a push button for the rear wash jets. I’ll let you know how I got on…