Dead Windscreen Wipers

[mogdobz]

Hi all, just shooting off a shot in the dark in case anyone has some wisdom about it. Doris' wipers failed today and no amount of staring at the button or pushing it in and out made them work again.

I set off in light rain. The car had been sat in a light shower for an hour or two. The wiper worked for about three minutes, then when I pulled up at a garage for petrol and switched them off they failed to park and sat halfway through a sweep. I switched them back on again to park them, and they did, then off again. Filled up. Started on the way again and switched them back on but they failed halfway through a sweep (in the same position they sat in when they failed to park a minute before). Since then dead as a doornail.

Never happened before, but the car is new to me, and I haven't needed the wipers much before now.

Tomorrow I am going to test the current and check for a blown fuse but I don't really expect the fuse to be the problem. Everything else (except the cabin light - a separate issue) is currently working.

Any tips for diagnosing this sort of fault? I was wondering how I'd check if the switch itself is the problem.

Thanks all for any advice.

[svenedin]

Is it a standard Morris 1000 wiper motor, Lucas DR3a?

The usual reason for wipers giving up in the way you describe is that the motor overheated due to having to operate with thickened old grease inside the gearbox part of the motor and/or a seized or partly seized wiper wheel box spindle. But I agree it makes sense to check all of the electrical connections and switch before a tedious strip down of the motor.

I am not familiar with the pull switch as my car is later and has a toggle switch.

The wiper motor itself has 3 electrical connections and it is very important not to muddle them up. One is earth and that is the black wire. Then there is ignition-on live which is green and the last wire is switched earth which is green/black. The reason for 3 wires is to enable the self-parking to work even when the wiper switch is turned off. For self parking to function there must be a permanent live which is the green wire (subject to the ignition being on). When the wipers are turned on at the wiper switch this completes the path to earth (switched earth) and the wipers then operate. Then if the wipers are turned off at the wiper switch the motor can continue to run until parked using the black earth wire path to earth via the internal self-parking contact.

So, to test if there is power to the motor you need to connect one multimeter probe to the green wire at the motor and the other probe to earth with the ignition on.

As for testing the switch all you need to do it determine that in the OFF position there is no continuity to earth from the green/black wire terminal to earth and in the ON position there IS continuity. You could also test continuity of the green/black wire by placing one probe at the motor terminal and the other at the switch.

Stephen

[mogdobz]

Is it a standard Morris 1000 wiper motor, Lucas DR3a?

The usual reason for wipers giving up in the way you describe is that the motor overheated due to having to operate with thickened old grease inside the gearbox part of the motor and/or a seized or partly seized wiper wheel box spindle. But I agree it makes sense to check all of the electrical connections and switch before a tedious strip down of the motor.

I am not familiar with the pull switch as my car is later and has a toggle switch.

The wiper motor itself has 3 electrical connections and it is very important not to muddle them up. One is earth and that is the black wire. Then there is ignition-on live which is green and the last wire is switched earth which is green/black. The reason for 3 wires is to enable the self-parking to work even when the wiper switch is turned off. For self parking to function there must be a permanent live which is the green wire (subject to the ignition being on). When the wipers are turned on at the wiper switch this completes the path to earth (switched earth) and the wipers then operate. Then if the wipers are turned off at the wiper switch the motor can continue to run until parked using the black earth wire path to earth via the internal self-parking contact.

So, to test if there is power to the motor you need to connect one multimeter probe to the green wire at the motor and the other probe to earth with the ignition on.

As for testing the switch all you need to do it determine that in the OFF position there is no continuity to earth from the green/black wire terminal to earth and in the ON position there IS continuity. You could also test continuity of the green/black wire by placing one probe at the motor terminal and the other at the switch.

Stephen

Brilliant overview, thanks Stephen.

However... My modern car woke up dead this morning, so it looked like I'd have to take its older colleague through rush hour. Not without the wipers though. Prepared to do some overtime to make up for it, I was just getting ready to diagnose with your advice - then I got them working again by jiggling one of the wires going to the motor!

I guess it's not always a big rigmarole...

Meanwhile my modern car gets to feel very sheepish until I can give it its own attention!

[svenedin]

Ah the old loose wire......

When you get a chance clean up the spade terminal on the motor with emery and check that the wire's connection to the terminal isn't failing. You might need to crimp on a new terminal as sometimes the strands in the wire fray so that the terminal is only being held on by a few strands.

Stephen

[Mog The Million]

Evening,

I'm the owner of Mog The Million (VDL 833), whose windscreen wipers also appear to be dead as a dodo. I'll ask the garage to read the info on this post to confirm it's not a connection issue, but assuming their diagnosis of a dead motor is correct, does anyone know, please, where I can source a replacement without it costing too much?

I believe it's a LUCAS DR2 wiper motor - I've seen one for £300 that's reconditioned and required me to swap a serviceable one for it, which I'm not sure I can do ... anyone got any clues as to how to do better than this? I get that it's a rare car and better to use original parts, but £300 for a simple motor seems a lot to my mind ...

Advice very welcome!

Thanks,

Aubrey

[svenedin]

The model type is stamped on the metal cover over the gearbox part of the motor.

Unfortunately, the reconditioned motors are expensive. ESM sell them on exchange.

Check the wiring as in posts above before assuming the worst.

There are various potential faults: bad electrical connections; seized wiper wheel box spindle(s); general excessive friction from old grease; worn out motor carbon brushes etc. It is possible for the motor windings to burn out which is terminal but many other possible causes that are fixable at home or by a competent garage.

If it comes to it, swapping the motor is not that difficult but it will not help if the rest of the system (wheel boxes, rack) are creating excessive load on the motor.

Stephen