[Alrt]

2003 ML350; the front wiper blade switch is off but from time to time the wiper blades make a snappy move e.g. like 10 mm at the time. After a few of those they make a one full swing and return to original position.

I assume the latter part is kind of "reset" i.e. the blades move above a certain limit and the system reacts to and resets the blades to correct position.

Any ideas what might be the cause? the blade motor, switch, relays or what?

This model does not have (to my understanding) a rain sensor so it can't be it.

Thanks in advance,

Ral

 

[43sqd]

I'm not taking a wild guess, but I would say that it is the Combination Switch.

 

[Alrt]

I'm not taking a wild guess, but I would say that it is the Combination Switch.

Why is that?

What should be done first to dig further about the issue

 

[43sqd]

By turning the wiper switch arm, it provides a 12v signal to close the contacts of the wiper relay, K17. So it can be safely assumed that the activation is coming from the Combo. Sw.

You can try swapping K17 relay with a similar one in the fuse box and see if that corrects the problem. If not.............

Remove the covers (3 screws) surrounding the steering column and while the wiper switch is off, tap the Combination Switch body with a screwdriver handle and see if wipers react the same.

 

[Alrt]

Changed the relay and also looked the switch but no help.

One day I noticed that when the blades move there is also a snap in central locking. Sounds like it would be trying to lock the doors at the same time. That sounds very weird since these should not have anything to do with each other but then I learned that there is a common nominator for both and that is AAM.

This makes me wonder whether AAM is somewhat involved. Could that be the cause and how to diagnose/troubleshoot AAM further?

 

[art_arev]

Have the car scanned for codes.

 

[alphonsohall]

I suspect that that the fault lies with the 'auto park' switching located within the wiper motor.

(Repair or replace wiper motor)