R129 wiper relay

[sixsix245]

Hello everybody, I'm a newbie posting here. Hoping for help with the mono wiper problem. Until recently the wiper worked only on full speed, it has now parked on the drivers side and won't budge, I can feel the 4 relays picking in the big casing behind the fuses (which are the spade type not bullet fuses) and even had this in bits, unsoldered a couple of relays, cut one open only to find it pristine inside. I did clean the contacts because I was there but as expected no change to the fault. Is there another wiper relay hidden somewhere on the car?

 

[Wearsafoxhat]

I think the speed is controlled through a rheostat but not sure where it is located. Usually a sign it is on its way out is the lack of lower speed selections. Oh and welcome...


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[mioba]

Welcome to the forum sixsix, enjoy the ride and do stick around.

Are you sure its not the gear on the motor, as the relays all seem ok.

 

[sixsix245]

Thanks for the welcome and the thoughts. I'm not sure of anything now, but I'm sure I metered the motor contacts at the start of the saga, but I will put 12 volts on it in the morning to test it. I've not seen any mention of a rheostat before today, where might I find that? TIA.

 

[sixsix245]

Well the next job is to take the wiper motor apart, it kills the 12volts and won't budge with 12 v jump to it. More as it happens.

 

[LostKiwi]

What year is the car? I'm guessing quite late as it's not "Euro" fuses

 

[sixsix245]

It's 1997 320sl

 

[sixsix245]

Nearly there. Took the motor to bits, cleaned the commutator and noticed one of the carbon brushes was not moving as I would expect--- never seen 3 brushes on a commutator before! Fiddled with the casing a little as the brushes appeared to still have lots of life left in it and now have a working wiper. I did not realise that the red and green were both 12 v feeds with the brown/ casing as negative. Perhaps a little further investigation as speed 2 and 3 appear to be the same. More as it happens and any advice welcome.