Wiper relay? Help me diagnose - PeachParts Mercedes-Benz Forum

benhogan · #1 02-02-2010, 10:49 AM

The wipers do not work. I am trying to narrow this problem down.

The multipurpose stalk controls the wipers, turn signals and the pump for the windshield washer.

The turn signals work but the wiper and washer do not.

Does this point to the multipurpose relay or the stalk itself?

The replacement parts for both are kinda expensive so I was hoping you guys can help diagnose.

I can take the relay out and bang it around. That sometimes helps. Is the stalk easy to remove and test with a multimeter?

Murkybenz · #2 02-02-2010, 12:37 PM

It could point to the wiper motor itself.

My other half has a 1989 w124 300d that has no intermittent function but would work on the other two settings and then it slowly started to misbehave and refuse to work.

So I checked the relay and this can be heard to click when intermittent function is on and continue to click proving the relay is ok.

The wiper will work if given a prod and once working will continue 50% of the time to function.

I did expect that maybe the cold weather had stiffened up the grease in the mechanism but it turns out the wiper motor is just plain worn out and only has half the power it should,as I flooded the drive gear out with penetrating spray.I drilled 3 holes in the turtle shell cover and poked the can nozzle in,I was not going to remove the wiper unless I have another that works to replace it ready to fit.

Removing the wiper arm will see it work happily so I expect the brushes in the motor are worn out,not sure if this is anything to do with the intermittent function not working though.

I found by removing just part of the trim I could get a 13mm spanner on the motors linkage connection and then turn it until the wiper blade moved up the screen,from this position it would either work and return and park or just move part way and then sit for a few seconds before moving again.

The motor compared to the one in my 1990 300d sounds as if it is running at only half speed.

Graplr · #3 02-02-2010, 12:58 PM

I concur to look at the wiper motor or electrical connections to the motor. Next would be the stalk itself.

Definitely NOT the relay. The relay controls the intermittent function. If it goes bad the delay does not work but you still have wiper function.

benhogan · #4 02-02-2010, 12:59 PM

Quote:

Originally Posted by Murkybenz

It could point to the wiper motor itself.

My other half has a 1989 w124 300d that has no intermittent function but would work on the other two settings and then it slowly started to misbehave and refuse to work.

So I checked the relay and this can be heard to click when intermittent function is on and continue to click proving the relay is ok.

The wiper will work if given a prod and once working will continue 50% of the time to function.

I did expect that maybe the cold weather had stiffened up the grease in the mechanism but it turns out the wiper motor is just plain worn out and only has half the power it should,as I flooded the drive gear out with penetrating spray.I drilled 3 holes in the turtle shell cover and poked the can nozzle in,I was not going to remove the wiper unless I have another that works to replace it ready to fit.

Removing the wiper arm will see it work happily so I expect the brushes in the motor are worn out,not sure if this is anything to do with the intermittent function not working though.

I found by removing just part of the trim I could get a 13mm spanner on the motors linkage connection and then turn it until the wiper blade moved up the screen,from this position it would either work and return and park or just move part way and then sit for a few seconds before moving again.

The motor compared to the one in my 1990 300d sounds as if it is running at only half speed.

i forgot to mention that it is intermittent.

would that still point to the motor?

ArkyDoodle · #5 08-29-2010, 08:04 PM

Did you ever get resolution for this wiper issue? I'm experiencing the same thing (I think)....I pulled off the wiring connector on the firewall to the wiper motor, attached a grnd and hot wired to simulate medium & fast wiper ops (worked fine, motor OK). I then figured that it must be a wiring / connection issue between the firewall and the switch.....Nope, I got power to one of the pins when the wiper stalk was in either II or III position (low voltage on two pins when in I). So it appears that the wiring/connection/fuses are OK............But since it still doesn't work (at any speed, no washers either) I'm missing something!!!!