Richmac Posted May 19, 2022 Report Share Posted May 19, 2022 Hi All After just over 2 years ownership I got caught out by the rain last weekend and needed to use the windscreen wipers. All went well at first and I was quite impressed with how well they cleared the windscreen. I was using the on / off as a manual intermittent wiper but after a while the wipers wouldn't turn of. I still had two speeds but no off. We made our way back with the wipers going (still varying degrees of rain) and stopped for a coffee and then more worryingly as we went to set of I thought I could see smoke coming from the wiper switch vicinity as they set off again. I quickly turned of and removed the cutoff key. I then pushed the switch out of the dash and one of the wires was very loose. I made sure the wires were all pushed on properly and this seemed to get them to turn off so didn't use them the rest of the way home. I did notice whilst trying to turn them off before the settings seemed to be down off, middle fast and up slow which seemed weird. Back in my garage and on inspection there appears to be no damage done to the wiring but looking at the connections the wiring doesn't seem to correspond to the manual. I have searched on here and it looks like I have a replacement Lucas switch and Dingle from 2011 suggests they are wired different to both the manual and how mine was. I have also read that if you get the wires the wrong way round you can cook your wiper motor!! So my questions are please 1. Is it possible to test the switch with a micro meter to see if its faulty if so how ( I have a micro meter but absolutely no idea how to use it ) 2. What is the correct orientation of the settings 3. With the lucas switch are the colours for the connections as the manual or as Dingle suggests here https://www.tr-register.co.uk/forums/index.php?/topic/32172-replacement-cp-wiper-switch-wiring/ Thanks for any help Regards Richard Quote Link to post Share on other sites
RobH Posted May 19, 2022 Report Share Posted May 19, 2022 There is info on the connections in this recent thread: If you switch your multi-meter to the ohms range you can use it to test the switch. Connecting the meter leads directly together will show a reading near zero so by touching one to each of the switch tags you can see what connects to what. In the off position pin 4 should connect to pin 3 In the slow position pin 2 should connect to pin 3 in the fast position pin 1 should connect to pin 2 Quote Link to post Share on other sites
Richmac Posted May 19, 2022 Author Report Share Posted May 19, 2022 Thanks for your help Rob. So to be clear pin 3 is the one without a terminal connected on my switch? If I connect as you suggest with 2000n to 3 pin (without a terminal) I do indeed get a circuit. This would suggest then that pushed up should be off, middle on and down fast? As in the picture would be fast. So if I connect as the thread and the manual to this switch this is how it should be? Quote Link to post Share on other sites
Steves_TR6 Posted May 19, 2022 Report Share Posted May 19, 2022 Rob is correct, as usual with anything electric! the tr6 wiper circuit is actually quite sophisticated, so do be sure not to connect the wiring incorrectly when testing else the lucas smoke may escape. here’s a diagram that explains how they (should) work steve Quote Link to post Share on other sites
Richmac Posted May 19, 2022 Author Report Share Posted May 19, 2022 Thanks Steve. 3 minutes ago, Steves_TR6 said: the tr6 wiper circuit is actually quite sophisticated, so do be sure not to connect the wiring incorrectly when testing else the lucas smoke may escape. This is what worries me!! You can see it was wired totally different before Quote Link to post Share on other sites
RobH Posted May 19, 2022 Report Share Posted May 19, 2022 There are a variety of lucas type switches Richard. The drawings are as it should be but obviously your switch isn't like that. If you can measure how the switch tags connect in the three switch positions, and post it here, we can work out how it ought to be connected. Quote Link to post Share on other sites
Steves_TR6 Posted May 19, 2022 Report Share Posted May 19, 2022 1 minute ago, Richmac said: Thanks Steve. This is what worries me!! You can see it was wired totally different before Indeed! if you study the picture it has the colour codes for the wires so you can see what they do : green is 12v ignition Controlled to the switch red with light green is low speed power to the motor brown with light green is the park control from the motor blue with light green is fast feed to the motor the cleverness is in the park switching, and often the park switch in the motor fails causing consternation good luck getting to the bottom of your issues ! steve Quote Link to post Share on other sites
Richmac Posted May 19, 2022 Author Report Share Posted May 19, 2022 Thank you for trying to help me but I'm sorry I don't understand 'Measure the switch tags'? Quote Link to post Share on other sites
RobH Posted May 19, 2022 Report Share Posted May 19, 2022 OK I think I have found the information by searching the web. I believe the switch you have is a Lucas 39736 equivalent and the connections are almost the same as the standard switch but missing out pin 3: position 1 (off) - 4 to5 position 2 (slow)- 2 to4 Position 3 (fast) - 1 to 2 That means you need to connect the wires like this: Blue/light green to pin 1 Green to pin 2, Red/light green to pin 4 Brown/light green to pin 5 Quote Link to post Share on other sites
Richmac Posted May 19, 2022 Author Report Share Posted May 19, 2022 Wow thank you. There is a number on my switch 39748A1094 Quote Link to post Share on other sites
RobH Posted May 19, 2022 Report Share Posted May 19, 2022 Yes that is the same contact arrangement - the different type number is just the surround and logo. Quote Link to post Share on other sites
Richmac Posted May 19, 2022 Author Report Share Posted May 19, 2022 If I connect my micro metre to the terminals as you suggest, set on 2000k, seems to check out. Gives me a circuit and reading drops from 1 to zero. Time to try it on the car then. Thank you so much for helping me really appreciated Quote Link to post Share on other sites
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