Wiper Motor Connections

[bcmc33]

I am in the process of fitting relays for the electric windows and wiper motor to protect the switches from potentially high inductive loads. The circuits I?ve drawn up are quite simple, but I have a concern with one of the wiper connections that I am sure someone out there will know the answer.
There are four (4) live connections to the wiper motor:-
White/green ? live feed to the switch and live to the motor. (I assumed that this was power for parking wipers).
Blue/green ? switched live for normal speed.
Brown/green ? switched live for fast speed.
Red/green ? switched live to motor when switch in off position. (Am I to assume that this is power for parking wipers?).

My question; why are there two (2) live connections going to the motor when the switch is off as there is continuity between white/green & red/green connections?


Brian Clarke
(1972 Sprint)

[iain.hamlton]

Brian

Please look at the attached diagram. This adds a relay to stop inductive loads affecting the switch in slow and park modes, while keeping the self park function. It means you can "flick-wipe" without frying the switch, or you can easily add an additional flickwipe or intermittent switch. You could add an additional relay for "fast" if you wish. Other benefits are that the cable runs are shorter, and therefore volt drops are smaller, and that most of the work is accessible under the bonnet rather than behind the dash.

best regards, Iain

[bcmc33]

Iain,

Thanks for the info, but I already had your cct diagram from an earlier post which only added to my current confusion.

Although your cct shows four connections to the wiper motor, the switch only shows three connections. You don?t show where the switch park connection goes. i.e. the red/green cable.

My question still remains as to why there are two live connections to the wiper motor in the switch park position.

Could it be that the switched park live (R/G) is not necessary? I had originally assumed that the common live supply (W/G) to the switch and motor was for the purpose of parking the wipers in the switch off position. It was only when I traced the complete cct that I found there were two live connections to the motor in the switch off position.


Brian Clarke
(1972 Sprint)

[john.p.clegg]

Iain

My diagram shows only one perm to live terminal 4 of the motor,which is fed back via the park contacts ( terminal 2) to the switch "off" (terminal 1)back to the motor via switch 2 to terminal 5 (motor) which slow drives the wipers to park.

When parked you have live on terminal 4 (motor) only....

Confusing isn't it

If only I could scan the diagram I have to you...

John

[iain.hamlton]

Yes and no.... There should be four in the standard set up, but I only use three at the switch. Effectively the fourth stops at the relay.

For normal operation you use 12 volts from the ignition switch. For parking you can use unswitched 12 volts, so the wipers park even if you turn off the engine. Secondly, the parking 12v is not present unless the wipers are physically in the park position. If this is case, when you turn off the wipers, they continue to be powered through the switch until they are parked. I have seen an diagram of this on an MG site somewhere....

best regards, Iain

http://www.mgb-stuff.org.uk/wiper2.htm

[iain.hamlton]

This is a better diagram....

http://www.mgb-stuff.org.uk/wiper4.htm

best regards, Iain

[bcmc33]

Iain,

Many thanks - this answers my basic question quite clearly even if the Lotus manual switching is different from that shown for MGB.

I guess the park switching is done inside the motor using the two live connections.


Brian Clarke
(1972 Sprint)