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Intermittent Wiper/washer Question


sirius815

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Hi guys,

 

I am in the process of doing a partial rewire on my '02 and had a question about the windshield wiper operation in relation to the windshield washer pump.

 

I know the washer pump gets activated through grounding at the turn signal stalk ('73 model).  I am assuming this also turns on the wipers at the same time and how long do the wipers stay on after the stalk is released?

 

I am trying to put relays for both the pump and the wiper relay, however I don't have a 100% clear understanding of the wisch-wasch relay yet.  Main problem I can see with relaying the wisch-wasch relay itself is that operation of the washer pump relay would also have to operate the wisch-wasch relay....

 

Any help?

 

Thanks,

Ben K.

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I am assuming this also turns on the wipers at the same time and how long do the wipers stay on after the stalk is released?

The number of wiper sweeps depends on how long you hold the stalk to activate the squirter, but you usually get 2-4 sweeps.

John in VA

'74 tii "Juanita"  '85 535i "Goldie"  '86 535i "M-POSSTR"  

'03 530i "Titan"  '06 330ci "ZHPY"

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There is a time-delay relay on the firewall that controls the timing of the activation of the wiper motor relative to the washer pump. The pump itself is not on a relay.

 

Activating the stalk switch grounds the pump (turning it on), but simultaneously grounds and activates the time delay relay turning on the wiper pump. The delay relay function is controlled by a bimetallic strip in the relay so how long you activated the pump determines (to some extent) how long the wipes stay on. A short stalk pull doesn't heat the strip long enough for the delay function to kick in and so the wipers will go off immediately. A longer pull will activate the strip and the delay function usually for 2-3 sweeps.

 

If you want to get fancy, you can replace the old-style time delay relay (which may not even be available anymore) with a digital time delay relay to accurately control the interval...

 

PS: Later models have a intemittent wiper switch at the stalk and are wired a bit differently.

Rob S
'69 2002; '04 330i ZHP; 2018 X1; 2014 535i; 2017 340i

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^^ What I find interesting is that I never saw this bimetallic relay when I pulled everything from the engine bay...my car came without the washer pump...ironically enough, the wiring diagram I'm looking at does not have the bimetallic relay on it either...and it uses the 6 pin wisch-wasch relay, not the 7 pin...

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I re-read your original post and it sounds like you have a later model 12 fuse car. In those the wiper speed/intermittent function and pump delay are controlled  by a single module. I haven't disassembled or played with one, but just looking at the circuit diagram, you couldn't add a single relay to it without messing up the functionality (or getting overly complex). I suppose you could put a separate relay on the pump to isolate it, but the washer pump itself is low current draw and really doesn't need a relay...

Rob S
'69 2002; '04 330i ZHP; 2018 X1; 2014 535i; 2017 340i

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That is correct, my car is a 12 fuse car.  I was afraid that relaying the washer relay would make it over complex.  

 

Another question - what is the purpose of the brown-red wire going from the wisch-wasch relay to the wiper motor?  Is that part of the park mechanism?  The brown-red wire looks like it connects to the black-red wire through the wisch-wasch relay when the relay is not energized.

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