Monday, August 24, 2009

2 speed windscreen wipers

I have featured an article by Erikis Skinkis for sometime now on my website. Recently Geoff Morgan from Australia contacted me to suggest an improvement.

I am not an automotive electrician, but I have wired my own kit car completely, which includes connecting up a Lucas 2 speed wiper motor without the luxury of the original loom and switch. Some information was obtained from the net, some by bench testing for confirmation.

The diagram below shows how to wire up the 2 speed wiper motor using two single pole double throw (5 pin) automotive relays. The isolating switch used below is a simple 2 pole switch in which both output pins are live in the fast position. Relays do not have to be used, but if using a switch it is important to use the correct Lucas wiper switch (part No #35927). The Lucas motor stops in the park position very suddenly by shorting the windings to ground and if the correct switch is not used, you will blow fuses or worse.

If you are not 100% certain of the identity of the wires in the connector plug (there are various colour combinations) I strongly recommend you do a bench test.

Geoff Morgan

Here is the circuit diagram from Erikis which only has 1 relay.