Lotus Elan

two speed wiper motor

PostPost by: bob_rich » Fri Feb 25, 2011 10:43 pm

Hi Folks

Trying to understand something prior to wiring up the windscreen wiper motor. Have two questions and depending upon the answers might clear up some confusion I have

Q1 Do the wipers self park on both normal and fast positions?
Q2 Is the wiper switch a centre off type with normal up and fast down?

My switch is as Q2 and I cant see how self parking can work in both positions.
Car is a December 1973 +2S 130

cheers

bob
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PostPost by: Higs » Fri Feb 25, 2011 11:03 pm

Wipers will self park when they are turned off using the switch. They will not park if the ignition is turned off when they were wiping. Here is a explanation of how the wiring works for wiper motors:

http://www.vtr.org/maintain/wiper-problem.shtml

Hope this helps.

Richard
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PostPost by: rdssdi » Fri Feb 25, 2011 11:13 pm

The park circuit is powered by a 12V+ un-switched circuit. When "OFF" is selected on the wiper switch the internal park contact and slow motor winding are connected to ground completing the circuit. This will run the wiper motor at slow speed until the internal park contact breaks the circuit stopping the motor when the wipers are in the proper park position.

Bob
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PostPost by: stugilmour » Sat Feb 26, 2011 2:18 am

Q1 Do the wipers self park on both normal and fast positions?
As described above by Richard. :) They self park in the off position at essentially a normal speed.

Q2 Is the wiper switch a centre off type with normal up and fast down?
No. The flat switches in my car are off, 1st speed, second speed. i.e., the centre position is first speed.

This link has some info I found helpful on the Lotus two speed motor. Somewhere I have a pdf of the original article, but this link info may be enough to help.

http://www.s-v-c.co.uk/prod_wipers.html

Assuming you have the flat switches, according to my wiring notes the switch configuration is as follows (viewed from back). Depending on your exact model, your wire colours may be different. However, the wire colours outlined at the link above on the wiper motor plug should be consistent with the switch functions listed below. Lotus (at least on the Federal model) used non-standard wire colours for this circuit; the colours I am listing first below follow Lucas (British Standards Institution # BS-AU7) standard, which appear to agree with the Triumph link. Your model, which is later than mine, may have corrected this minor confusion, and you may have standard wire colours? Let me know if this is too confusing and I can check details for your model's wiring diagram if it will help. I checked my wiring diagram for Plus 2S and inserted your expected wire colours below with question marks.

Switch Terminal - Wire Colour - Function - Triumph article equivalent switch terminal

Upper Left - Green (Green on Lotus Federal), Brown / Purple on your car? - power supply wire from fuse; Powers the switch - Terminal 2
Upper Right - Blue / Lt Green (Lt Green on Federal Lotus), Black / Red on your car? - Fast Speed; Powers motor @ fast speed - Terminal 1
Lower Right - Red / Lt Green (Yellow on Federal Lotus), Yellow on your car? - Slow Speed; Powers motor @ slow speed - Terminal 3
Lower Left - Brown / Lt Green (Black / Yellow on Federal Lotus), Black / Yellow on your car? - Park; * Terminal 4

* Didn't quite figure this one out but it works! Clearly Bob & Richard have a better handle on this mystery. I looked over Richard's link to try and figure it out, and seems to connect the power from the motor plug to the slow speed motor wire until the park position is reached. The park switch cuts power to the motor, and grounds the slow speed power wire. This grounding will stop the motor rotation immediately, so it doesn't run past the park position. Thanks for the great link; I have updated my notes. 8)

HTH As with all Lotus wiring, your mileage may vary. It's cold here and I have plenty of time, so apologize for length. :D

Quick adder. Once you figure out the wiring, a new plug for the wiper motor is available. Mine was connected with individual spade connectors , perhaps by to PO. I changed it over to the proper plug so it wouldn't get buggered up again.
Stu
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PostPost by: bob_rich » Sun Feb 27, 2011 11:31 am

Hi All

Thanks for the very useful info. I am pretty certain that my wiper switch wiring was never correct and that the wrong type of switch has been used in the wiper position. Currently I am stripping the whole lot down ( the wheel boxes were almost ceased up) and examining the parts and will work out the circuit I have and the best way to deal with it. Will post again to update U all when I worked out the full story

One again thanks for a very useful selection of info

cheers

Bob
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PostPost by: stugilmour » Sun Feb 27, 2011 7:34 pm

Happy to help Bob. The stock switches come up on FleaBay periodically if you require one. If you are really in a pinch, Ray at RD (rdent.com) lists replacements, although they apparently need some fettling to fit the stock dash and may not match the patina of your other switches if you only need one. Who knows, maybe the PO used the wiper switch in another location on the dash by mistake? Good luck with the re-wire.
Stu
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