Intermittant cycle (wipers) not working, just a steady back & forth sweep. Wonder what the problem could be?
Also, at times w/wipers in auto... wipers will not start. Have to put in off position, then to auto (to start).
Thanks

Those are the first signs. It will most likely get worse from here until the wipers completely die.

MB has had wiper motor issues on their w163 MLs...it's about a $550 repair at the dealership & $400ish at an Indy shop...

$300ish if you DIY...

So it's the wiper motor causing this condition..... thanks

Yep. The wiper motor, wiper gears & wiper speed controller are all one assembly. It is actually either the motor, gears or controller that has gone bad, but you gotta replace the entire unit.

In most cases it is the wiper motor. The motor is known to fail between 50k & 100k miles timeframe. The updated replacement wiper motor is supposedly better build quality & less likely to fail again.

I had to replace my wiper motor on the 2000 ML in 2006 at around 90k miles for the same issue.

The 03 has auto wipers? As in they come on when it starts to rain?

That is just a sensor near your central rear view mirror pointing outwards to the windshield. It detects the water droplets falling & turns on the wipers.

To isolate the wiper motor as the root cause, I would put the wipers in full manual mode & check if you have any issues. Intermittent, on/off etc.

If you can document any problem in the full manual mode, the wiper motor is the culprit.

If problems only surface in auto mode, maybe the sensor has developed a fault. I think, the actual control of the wipers in auto mode should be done by the ECU. Doubt if ECU would have developed a wiper specific fault.

Relay K17 operates the Intermittent Wipers. Swap it with a similar relay in the box and see if that corrects the condition. Make sure you replace the swapped relay until you get a new one for the wipers.

Thanks for the information.

Yesterday, in light rain, in auto setting, they worked fine. Today, in similar conditions may be a steady sweep in auto setting.
Think I'll try relay replacement 1st. But, aren't relay/fuses either good or bad? They work or they don't work..... no middle ground? Thanks again.

Not when it comes to relays.

Thank you....

how do you put them on auto? I don't see that option on mine

Auto feature depends on having a Rain Sensor which is standard equipment on ML 500 and 55's, which you should have.

Place the stalk in the intermittent mode and drive the vehicle. If you have a rain sensor (which you should) the wipers will not work every 5 sec.s or so. It will only do so when it senses water on the windshield.

The other reason for this feature not working is the sensor is missing, damaged or for some reason not actuated by the AAM.