Windscreen Wiper speed fault

[jdug]

Hi. I have a 1991 Safari Y60. The windscreen wipers work on intermittent and slow speed, but will not operate on the fast speed. I am not sure where to begin to test this fault. Is it likely to be in the switch or the motor unit? Any suggestions please

[4bye4]

As far as I am aware, there is live battery connected to the wiper motor from the ignition switch,Therefore the timing of the sweep or speed should be controlled after the motor. I would suggest that the problem is with the switch or the circuitry being switched. Similar setup to air fan speed settings.

[Yendor]

Wiper motors have two sets of brushes, one for low speed and one for high speed. The Patrols switch earth to the each brush to change the speed.

I'm not sure if the Safari wire colours are the same or not.

On Patrols the Light Green wire with the Red trace at the wiper motor is for high speed.

With the ignition on measure the voltage in this wire (plug still connected to wiper motor)

1. Wiper switch on low speed

2. Wiper switch on high speed

If you have 24 volts in both positions it's either a faulty switch or a break in the wire between the switch and the wiper motor.

If you have 24 volts on low and 0 volts high, it's a faulty wiper motor.

If you have 0 volts on low and 0 volts on high it's a faulty wiper motor.

If it does have 24 volts in both position you can try with some scrap wire connecting it straight to earth. Turn the switch to high speed and connect the wire between the Light Green wire with the Red trace and earth. Wiper motor should be running on high speed.

[jdug]

As far as I am aware, there is live battery connected to the wiper motor from the ignition switch,Therefore the timing of the sweep or speed should be controlled after the motor. I would suggest that the problem is with the switch or the circuitry being switched. Similar setup to air fan speed settings.

Thanks for the reply. I have not been sure where to start to look for a solution, but will do so then I get some time this weekend.

[jdug]

Hi Yendor. Thank you for your extensive reply with suggested step by step approach to identify the cause. I was a bit baffled by all the wires, but now I have a way forward. I will let you know how I get on.