ML320 - failing wipers
 

Hi , new to the forum , some great info flying around. I run a 98 ML320 here in the UK and have suffered from most of the common complaints I have seen posted up. My current aggravation is failing windscreen wipers. They just stop mid use and then start again ? Quite dangerous at 70 mph !! Any ideas ?? :(

Not that I will have a brilliant solution to the problem but, does the cycle consistently stop at the same position and, if so, where? Also, how long are the stops?

From what I can see , it appears to stop mainly in the intermittant mode and starts again roughly after 10 mins .

Dave -- is this an accurate synopsis of the problem?
- wiper motion never stops prior to three complete cycles after the switch lever/stalk is released when the wash mode is selected
- occasionally, wiper motion stops when the switch is set to either slow or fast continious wiping
- frequently, wiper motion stops when the switch is set to intermittant wiping
- when stops occur, the blades are parked in the normal position at the bottom edge of the windshield
- stops generally last about ten minutes and motion is resumed without any manipulation of the switch stalk.

Please correct any of my mistakes in this synopsis and add anything else that you can think of - if necessary, after your next drive in the rain.
I'll be out of town until the end of the month but in the meantime, it would be helpful if another member could chime in about where the timing function of the wipers is located. I can find nothing in any of my materials. Is it located in the combination switch on the steering column; at the wiper motor; or, in some control module? Surely, wiper control is not done with digital signal!

Geoff

AAM I believe is responsible for that (All Activity Module, located under the fusebox). MAY be a relay in the fusebox the AAM controls for this function.
What I remember is motor problems with these. If you can get it into a failed state, you can try tapping the motor with something like the handle of a hammer, you can pull up the front of the black plastic mesh screen to access the motor. If the wiper starts working after a few taps, it needs a motor

Gilly

Thanks fellas , just to confirm this is not related to wash wipe . These wipers stop whilst in use on both intermittant and normal wipe. When this happens I leave the switch on fast wipe waiting for it to resume , which it does after a period of no longer than 15mins.
Also I dont know if replacing the relay will help but the wiper action is quite poor , it passes below the resting place before parking 1 inch higher on a stop start motion instead of a continous smooth motion. Maybe related ????

Dave
There are a few things to try. First of all, *really* sounding like the motor to me.
OK, put it on intermittent wipe (in an operational state), and open the hood (watch to make sure the arms don't hit the hood) and open the fusebox. Hopefully by reading the fuse list, you'll be able to identify the relay for the wipers. With the wipers running intermittent, you should be able to put a finger on the relay and feel it clicking when the wipers cycle. Now, what you want to do is when the wipers fail, open the hood and do this again with the same relay, and see if it still is "clicking" occasionally, as though the relay is being operated. That'll pretty well take the AAM out of the picture; it's doing it's part. It could still be a bad relay output side, I think you may spot a few other relays there that have the same part number, as a test you can swap one into the wipers position on the relay board.
More than likely though it's the electric motor itself. Peep arounf the cowl and you should be able to gently pull up the black plastic cowl and get a slight amount of access to it. In a failed state with the switch on speed 1 (low speed, not intermittent) find something to fit under the cowl which will allow you to tap a few times on the motor, and see if you can get it to work. If that makes it work, I'd get a new motor.

Gilly

Thanks Gilly , I'll give your suggestion a try over the coming weeks.
Cheers

What about the rear wiper guys? I'm having an intermittent problem, and noise, at the rear - is there a separate motor in the tailgate I can replace, or is there another suggestion for diagnosing first?

On the rear wiper, sure there is a rear motor, MAN I've replaced an absolute TON of them. Usually it's a "squawking" noise as the wiper runs, really noisy.

Gilly

Gilly - that sounds like it then! Mine squawks both directions. Thank you!

Pretty easy to replace it too. Hardest part is getting the interior panelling taken off of the tailgate.

Gilly

If we are including the rear wiper too , I have the exact same problem , squaking in both directions ! Any chance of just putting lube in the damn thing?
Will this ML ownership ever reward me with a month where I have nothing to do !!

Nope, new wiper time. Well, that's what we always did in the shop, and MB always paid for them if they were under warranty, and we did lots and lots of them. You think if MB was paying the bill, if there was a way to fix them, they'd tell us.
Gilly