Wiper motor only works on fast speed

[mrscalex]

As title. No sign of activity from the wiper motor except when on the fast setting when it works as expected.

I know when stationary the wipers will only work on intermittent on all other settings but here they are not working at all.

Before I do the obvious and pull the glovebox out to replace the wiper module is there any views on if this is the most likely suspect? Anything else to check first?

 

[NZ00Z3]

I've had to repair one column switch for the wipers. It would not work on double speed. Two small rivets to drill out and it comes apart easily. Fitted small screws and nuts to replace the rivets when finished.

 

[mrscalex]

I've had to repair one column switch for the wipers. It would not work on double speed. Two small rivets to drill out and it comes apart easily. Fitted small screws and nuts to replace the rivets when finished.

Thanks. If you think there's a realistic chance it's the stalk I'll look their first. I have a spare I think.

 

[NZ00Z3]

You have to remove the under dash cover to replace the module and also to test the switch, so it comes down to the parts you have on hand. Swapping in a module is easier than testing the switch.

 

[mrscalex]

To be honest having only just put all the interior back I don't want to pull the glove box out unless I have to. Purely psychological rather than logical!

 

[t-tony]

I would first try disconnecting the plug at the wiper motor, the, using a power probe see if the motor works on all speeds by powering the contacts. I had the same problem on my mates Transit Connect a few weeks ago and this is where we started. After proving the speeds by using the power probe I sprayed contact cleaner on the plug and connector on the motor and all worked ok.

Tony.

 

[mrscalex]

I would first try disconnecting the plug at the wiper motor, the, using a power probe see if the motor works on all speeds by powering the contacts. I had the same problem on my mates Transit Connect a few weeks ago and this is where we started. After proving the speeds by using the power probe I sprayed contact cleaner on the plug and connector on the motor and all worked ok.

Tony.

Will certainly give that a go if stalk and wiper module not at fault.

 

[mrscalex]

Well we're left scratching our heads. Stalk, wiper module and motor all replaced and same problem. And this is on the new loom car so I think it's unlikely to be an issue with wiring as it's all brand new. I've also tested the outputs from the stalk and and all correct. And all the grounds and lives to the wiper module. We've had 2 different wiper modules on there including a known good one.

I guess perhaps I have 2 duff motors. So I'm going to work out some diagnostics with the meter at the motor and go from there.

In the meantime and I guess it's obvious if we think about it but this is how the system modes work.

1. Fast
2. Normal
3. Intermittent
4. Single/flick wipe

Motor 2 speeds only. Fast & normal.

The wiper module is a smart relay. It actually does quite a lot of stuff. To create the 4 modes above:

1. Send fast request to motor continuously
2. Send slow request to motor continuously
3. Send slow request to motor, rest, send slow request
4. Send slow request and then switch off.

Given that modes 2-4 all use the slow motor operation, this accounts for why we have the problem we do. The fast motor operation works. The slow motor operation doesn't however you serve it up.

The module also takes a speed input from the dash and while stationary the normal speed is reduced to an intermittent operation only. It also controls the washers for both windscreen and headlamps.

So we'll concentrate now on ensuring that the slow motor operation signal is being generated correctly by the module - which may in itself be working but may have a duff input from somewhere else. And that this is received by the motor - ie no issues with wiring. And we'll hot wire the motor to see if it operates on directly on slow.

 

[Pingu]

Use a test bulb (not a voltmeter) at the wiper motor location.

Normal signal wire to bulb to earth(*) - if it lights as expected in conditions 2-4, the problem is with the motor.


A voltmeter will indicate 12v if just a single strand of wire is there, a test bulb won't light.
(*) as the fast speed works, you know the earth return is good, so you can use any earth for the test.

 

[mrscalex]

Use a test bulb (not a voltmeter) at the wiper motor location.

Normal signal wire to bulb to earth(*) - if it lights as expected in conditions 2-4, the problem is with the motor.


A voltmeter will indicate 12v if just a single strand of wire is there, a test bulb won't light.
(*) as the fast speed works, you know the earth return is good, so you can use any earth for the test.

Good advice. Thanks.

 

[Mario]

Another idea, just in case the advice from Pingu does not help you fix the issue, "what if" even though the wiring harness is new and there shouldnt be any problems with continuity of cables there is a problem not with the wires themselves but with how the connectors have been wired and there are some cables that have been swapped. at the inputs of the relay etc not sure if that could make it work just on fast.

 

[Andyboy]

I bought a new indicator stalk from BMW for an E34 4 years ago and had to remove and refit wires in the plug to get the OBC to work - BMW tend to 'improve' things without notice. The old loom and a wiring digram will help.

 

[mrscalex]

I bought a new indicator stalk from BMW for an E34 4 years ago and had to remove and refit wires in the plug to get the OBC to work - BMW tend to 'improve' things without notice. The old loom and a wiring digram will help.

Interesting thought that. Although in fairness I’ve never come across it on a Z3.

We spent several more hours yesterday. It’s definitely not the motor as we put a power probe on both terminals and it ran fine. It’s not the wiper module as we used a known good one. And the stalk is sending the correct outputs to the module suggesting it’s neither the stalk or any connectors/wiring between.

It greatly helps having another car to compare to. So we’re going to back probe the module connector on all 15 pins on both speeds on both cars today to see if we can pinpoint it.

My gut feel is one of the inputs to the module is not right as something may not be plugged in correctly.

 

[Andyboy]

Are you sure it's not an earthing fault?

 

[mrscalex]

Are you sure it's not an earthing fault?

It may well be as the wiper system relies on ground switching. And the normal speed uses a different ground. So we're pulling off some more plastics to look at that today. But the multi-meter is telling us all is good at the wiper module - if I've understood all the statuses on the pins correctly. That said the wiper module is surprisingly complex. And because of the ground switching you need to understand not just what pins it should be present on but when as well. To complicate it further there is also a ground switch to park the motor as well as run it.

 

[mrscalex]

ABSOLUTELY UNBELIEVABLE!!

8 hours in and the only clue from the multi-meter being voltage on the headlamp washer pump pin that shouldn't be there. But as we have no headlamp washer system it was ignored right up until desperation struck. So what, in the course of changing the loom, might we have wired up wrongly to make the wiper module think we had a headlamp washer system? Just in case that fixed it...

The clue is here. The washer pump part of the wiper module connectivity. The black line on the left. I ignored it the first 99 times I looked at it then realised it was possible it was a jumper. So off I went to the known good car and what do we find? A jumper cap on the end of the headlamp washer pump connector... Sure enough, swapping it onto Willy it fixed the issue. And just for good measure we looked for it on the old burnt out loom and found it.

So there you go. BMW supply everything ready to go with a new loom except for this stupid jumper cap (61138380192) that feeds a ground into the wiper module. It really would be sensible to include it because if you do have a headlamp washer system you'd remove it to fit to the pump. If you haven't got the system then, well this situation is highly likely to result! To the best of my knowledge I can't think of anywhere else on the loom that uses a jumper for a non-present fitting. So it just didn't occur to me. Bizarre.

 

[Mint]

ABSOLUTELY UNBELIEVABLE!!

8 hours in and the only clue from the multi-meter being voltage on the headlamp washer pump pin that shouldn't be there. But as we have no headlamp washer system it was ignored right up until desperation struck. So what, in the course of changing the loom, might we have wired up wrongly to make the wiper module think we had a headlamp washer system? Just in case that fixed it...

The clue is here. The washer pump part of the wiper module connectivity. The black line on the left. I ignored it the first 99 times I looked at it then realised it was possible it was a jumper. So off I went to the known good car and what do we find? A jumper cap on the end of the headlamp washer pump connector... Sure enough, swapping it onto Willy it fixed the issue. And just for good measure we looked for it on the old burnt out loom and found it.

View attachment 196583

So there you go. BMW supply everything ready to go with a new loom except for this stupid jumper cap (61138380192) that feeds a ground into the wiper module. It really would be sensible to include it because if you do have a headlamp washer system you'd remove it to fit to the pump. If you haven't got the system then, well this situation is highly likely to result! To the best of my knowledge I can't think of anywhere else on the loom that uses a jumper for a non-present fitting. So it just didn't occur to me. Bizarre.

View attachment 196587

View attachment 196585

Well done Rob, that took some finding. I'm well impressed

 

[t-tony]

Me too, that was impressive mate.

Tony.

 

[mrscalex]

Thanks chaps. Just determination never to be beaten and have to call a pro in.

I have to say the more I think about it the more unlike BMW it is to use a fitting like this. Then leave it off a new loom. They are usually so on the ball with things like that.

 

[DrWong]

Deeply impressive detective work that