| Author | Message | ||
     Geoff Wootton Grand Master Username: dounraey Post Number: 478 Registered: 5-2012 |
I am having difficulty in figuring out how the windscreen wiper motor goes into reverse when the wipers are switched off. If I switch them off from normal speed, for example, the wipers will continue their sweep to the on screen park position but the motor will not then reverse to move the wipers to the off screen park position. For the motor to reverse, the polarity at the brushes of the motor must be reversed. I can't work out how this reverse in polarity is achieved. I know there are two control boxes under the top roll, but they are for the wash/wipe system and the intermittent wipe system, both of which work fine on my car. Has anyone any suggestions of how this reverse polarity is achieved. Geoff. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1057 Registered: 6-2009 |
Geoff, Do a forums search on "Lucas 16W". The first thread that turns up has an excellent article by Jeff McCarthy that should prove useful to you. The other three threads that turn up also discuss the Lucas 16W wiper motor and the wiring for same. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 480 Registered: 5-2012 |
Hi Brian I had checked through the forums and have a copy of Jeffrey's document, however I am trying to understand how the polarity is reversed on the motor brushes. I am aware of the two parking switches. The one beneath the cog-wheel to sense when the wipers have finished their stroke after the wipers have been switched off and the one on the slider arm to adjust the position of the off screen parking of the wiper blades. I think its becoming obvious to me that there must be a controller that is carrying out the reverse polarity switching to the brushes (if indeed that is the mechanism), so it looks like the top roll will have to come off. I was kinda hoping the polarity was reversed by one of the parking switches, but it appears this is not the case. Geoff. | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1058 Registered: 6-2009 |
Geoff, See Chapter M6 of the SY2 Workshop Manual. It gives a good explanation of how the various components, including the control unit, interact to reverse the motor. I'm not seeing the same information in the SY1 Workshop Manual. Given the vintage of your car it's almost certain to be very similar, if not the same, as the SY2s with regard to the windshield wiper functioning. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 481 Registered: 5-2012 |
Brian Thanks for that pointer - I have not checked the SY2 manual. Geoff | ||
| Bob uk Unregistered guest Posted From: 94.197.122.87 |
I don't think the motor goes backwards. The wiper gear box has a mechanism inside it, the. mechanism is controlled by a relay(s) behind the dash under the roll pad about centre. Mine works fine but sometimes does turn off. If the switch is turned back on and off then it parks. It's like I have turned the wipers off in the wrong part of the cycle. On the screen.wash it works fine. I had a 1959 Rover P4 100 and that had the same system. I think it's the.same as a shadow. I have never worked on a shadow wiper system so I can't be sure. The Rovers wiper motor was earthed on one of the motor brushes so reverse would not be possible. Inside is a series of contacts and most likely the problems lie with those switches. To set most wiper parking system made by Lucas and Smiths is to loosen the round bit with the park switch wire coming out of it and turn the round bit ( about 2" in dia) with the ignition on and the wipers follow the turning when they park correctly tighten the screws and test. The shadow is more complicated though because like the Rover it goes further when it parks. I must repeat that I am not sure but my 1974 shadow's wiper motor appears to have a similar arrangement to the Rover. (Message approved by david_gore) | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 1059 Registered: 6-2009 |
Bob, The motor does go backwards (or at least it does on the SY2s). Watch it do so in this video from SRH33576. Brian | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 482 Registered: 5-2012 |
Bob, SY1's the same - the motor reverses. One of the reasons I want to get mine working, apart from the fact it would be nice to see where I'm going, is it is such a lovely action when it parks. I have seen this on the XK150 I once owned. A long time ago I had a Rover P4. It was the 1954 model and had a freewheel device fitted as standard. Loved it. You could coast down all the hills on tickover. I believe they were legislated against in the UK as they were deemed to be so dangerous. Geoff | ||
| Bob Reynolds Prolific User Username: bobreynolds Post Number: 163 Registered: 8-2012 |
It is very difficult to work this out from the circuit diagram, as the arrangement of the various switch wafers is complete guesswork. When I switch my wipers off, they continue to the On-Screen parking position and the On-Screen switch reverses the direction of the motor. At the same time, I can hear a relay behind the dashboard clicking. There are no relays shown on the diagram, so it's possibly the one in the Intermittent Wipe unit. When I was adusting my wiper motor earlier this year, I remember that sliding the On-Screen parking switch backward and forward also reversed the direction of the motor. You could check the adjustment of the parking switch, as if it is not right it will prevent the motor from reversing. (Page M77 & M78) | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 485 Registered: 5-2012 |
Hi Bob This is what leads me to believe one of the control units must be responsible for the motor reversal. When the windscreen wipers are on the On-screen switch is sending a signal to the controller once per revolution of the cogwheel. When it detects the dashboard wiper switch has been turned off and the cogwheel switch is also off it must then reverse the polarity of the wires that connect to the motor brushes. This is of course pure conjecture, but I cannot see any other way in which the system works. I have been reading the SY2 manual, at Brian's suggestion, even though my car is an SY1 and it appears the relays mentioned in this manual are on my car. I am currently checking them out. I could find no reference, even in the much more comprehensive coverage of the SY2 manual, of the operating principle of the wiper motor reversal. However, there is a function table that diagnoses a parking reversal problem as a faulty relay. This is the only reference to the park off screen function. Geoff | ||
| Bob uk Unregistered guest Posted From: 94.197.122.82 |
I have had a good look at my wiper and the workshop manual and it is nothing like the Rover one. The wiper motor does reverse. There is a switch on the circuit diagram which connects a brush to earth or live. This may be the faulty bit. The switch is next to the motor on the circuit diagram called park. It appears that the switch is inside the wiper motor gearbox. Or the relay as Mr Wooten explained is the problem. Lucas can be so fiendishly complicated. Stick to rocket science. (Message approved by david_gore) | ||
| Michael Mangan Unregistered guest Posted From: 184.15.181.40 |
I have a slightly different problem, it has just started. When the wipers are switched off, they do not stop.They continue very slowly. My car is LRA 14501 1972 long wheelbase. (Message approved by david_gore) | ||
| David Gore Moderator Username: david_gore Post Number: 2276 Registered: 4-2003 |
Michael, try spraying the wiper switch on the steering column - the contacts may be contaminated with either a conductive contaminant and/or residue from worn contacts. Do this after cleaning the fuse board connectors as detailed in my other reply concerning your indicator problem and then testing the wipers shut-off afterwards. The fact that both problems have occurred at the same time is a possible indication your car might not getting sufficient regular use to keep things functioning the way they should. Above all, R-R/B vehicles thrive with regular driving; if they are not driven frequently, a common form of protest is niggardly electrical problems. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1447 Registered: 5-2012 |
Michael Could you describe more precisely what's happening when you turn the wipers off. On turning the wiper switch off, do the wipers return to the off screen park position but then keep wiping, or do they just carry on wiping, but more slowly, from the on-screen park position. This information will help diagnose the fault. Geoff | ||
| Jeff Cheng Experienced User Username: makeshift Post Number: 39 Registered: 2-2016 |
Michael, my wipers are showing the 'slow movement when switched off' at the moment. With your wiper motor cover off and the wiper arms lifted off the screen, can you see the motor gear reverse to park the wiperd when you switch them to off? I ask because with the wipers in the air, mine work as they should, quite swiftly then reverse to park. However, with the blades on the screen, the return to park seems reeaaaally slow, as if the extra drag of the wiper blades is too much. So much so they end up 'parking' where the normal wipe ends anyway. Lift the arms back up and cycle the switch on-off and they park nice and quick. I've lubed everything I can and still puzzled, but I don't drive in the rain, so no biggie. | ||
| Geoff Wootton Grand Master Username: dounraey Post Number: 1448 Registered: 5-2012 |
Hi Jeff Have you lubricated the wheelboxes on your car. These are meant to be lubricated with a drop of oil every year. They can get very stiff. Any time you are working on the wiper motor it's worth pulling the cable out, pulling off the wipers and checking to see how much resistance there is to turning. They should of course be completely free. When I checked the wheelboxes on my car they were so stiff I was surprised the wiper motor moved the wipers at all. Since you have to remove the top roll to get them off the car I opted to just rotate them with my fingers whilst first using WD40 and after they became completely free, light oil. It took about 20 mins for each one to completely free off. What can happen is part of the rotation gets very sticky, which could explain why your reverse park moves so slow but normal wipe is much faster. Geoff | ||
| Jeff Cheng Experienced User Username: makeshift Post Number: 41 Registered: 2-2016 |
Geoff, I have lubricated what I can of the wheelboxes as per the instructions in the TeeOne topics of tying an oil soaked strip of cloth around the 'knob' where the wiper arms attach, then running the lot on high speed for 20 minutes to wick the oil down. What stumps me is that the wiper speed is good in both directions, only the park/reverse motion in slow. Almost like there is some resistance to the motor turning backwards. Wiper arms off the screen and everything looks good, but rubber on glass and the park motion struggles even though the 'normal' operation is good. I would have thought sticky wheelboxes would affect both normal operation and park. | ||
| Jeff Young Prolific User Username: jeyjey Post Number: 277 Registered: 10-2010 |
Hi Jeff, In that case, I would suspect a high-resistance connection somewhere in the reverse wiring that is lowering the voltage to the motor. Cheers, Jeff. | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 472 Registered: 5-2007 |
Jeff, For elimination purposes, if nothing else, the first thing I would check is the connections to the switch underneath the rotor/cog part of the motor. This switch has a button which is depressed with every turn of the cog but I believe it only becomes operational during the park sequence, probably triggered by the unit under the dash or by the park switch. In fact check the connections on the park switch while you're at it. These connections suffer from a fair amount of vibration because the loom "hangs" a bit. They also get filthy. If you replace the connectors it's imperative to use the correct type, as detailed in the article. Given the symptoms it's unlikely to be the under dash units - I'd eliminate all other possibilities first before removing them. And of course lubricating the wiper motor may help - it's possible a bit of hardened grease and/or grot is lodged in the cogwheel mechanism. Blast it with WD40 to clean it before adding new grease. Don't take the spring and cam mechanism apart though - unless you enjoy nervous breakdowns, 3D chess and doing Rubik's cube solutions whilst blindfolded on Tequila. | ||
| Martin Taylor Frequent User Username: martin_taylor Post Number: 54 Registered: 7-2013 |
I too had a 59 P4, it's wipers had small rollers to lift them over the edge of the windscreen seal when parking, they did actually park off the screen. Shadows do almost the same thing but have an "anti-streak" mechanism, this makes the wipers do a full wipe before reversing, this can sometimes not work if the screen is too wet for the clutch to slip and reverse the mechanism (it is entirely mechanical). So to park the motor is driven to its limit (full wipe, linkage towards screen), the relay drops in the control box and the motor is reversed until the park switch opens. if the clutch doesn't rotate the eccentric cam due to dry grease, broken springs, or super wet windscreen the wipers will continue to run, this is not a problem if it is caused by rain as you would want them on anyway. The SY2 cars are wired different as they have the intermittent function added, this is a different wiper switch, extra park switch and an extra control module. I have repaired quite a few of these on both Shadows and Rovers. | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 473 Registered: 5-2007 |
Martin, just a minor addition to your post. Later SY1 cars have the SY2 arrangement you describe and the intermittent function. Not sure when it changed, but my November 1974 has it, hence my post above. | ||
| Jeff Cheng Experienced User Username: makeshift Post Number: 42 Registered: 2-2016 |
Jeff, Jeff and Martin, That's interesting you mention SY2 cars with the intermittent function adding complication to the parking movements. My car is an early '76, with the intermittent function, so maybe I need to troubleshoot following SY2 procedures...? | ||
| Jeff McCarthy Grand Master Username: jefmac2003 Post Number: 474 Registered: 5-2007 |
Jeff, I'd do that definitely. A 1976 car will have many of the upgrades, especially electrical, of the early SY2. My electrician said mine was a SS one and a half. Also from experience it's always worth looking at the wiring diagrams one version later than your own car if something isn't clear or present on your own car's spreadsheet - especially with peripherals like wipers. | ||
| Bob Reynolds Grand Master Username: bobreynolds Post Number: 419 Registered: 8-2012 |
The wiring diagram for the 1974/5 Shadows (TSD 4028) does include the Intermittent Wipe Unit. So looking at a Shadow 2 wiring diagram isn't necessary, and will probably confuse matters! |
