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intermittent wiper rheostat troubleshooting

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Old 12-21-2010, 11:03 AM
  #1
ivangene
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Default intermittent wiper rheostat troubleshooting

well as the title suggests, I would like to know how to troubleshoot the rheostat for the intermittent wipers

A search yields a few posts but no real info, the bentley just tells me how to replace it and at well over $100 i dont want to start replacing good parts.

The symptoms: wipers work perfect on the stalk control but have started to have occational stopping mid-wipe while in intermittent mode - thought maybe I could clean the thing, but if I take it out I wanna know how to check it out.

are there more parts involved (ie a control unit/relay/ect) that might be suspect.

This is not going to need emergency repairs, but I would like to keep up as we all know little things can end up being overwhelming at some point
Thanks Guys.
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Old 12-21-2010, 12:08 PM
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Marc Gelefsky
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Why, get much rain?
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Old 12-21-2010, 12:09 PM
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we have switched from the old "inch" measuring method to the new "feet" method
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Old 12-21-2010, 12:28 PM
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geeez!!

We just have ccccccccccold!
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Old 12-21-2010, 12:31 PM
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From the workshop manual current flow diagram, there is a relay as well as the switch. Good luck tracing the problem!
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Old 12-21-2010, 12:41 PM
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i have never had the WW system out of the Porsche but on other cars I have done there have been microswitches in the motor asembly . This tells the wiper system the arms have returned to home. Not sure about the Porsche though. Even though I would go here last .. don't discount the motor as being the cause . In full on mode it would not even look at these switches until you turned it off then it would look to go home. on intermitent it looks to go home every time until it is told to go again . I don't know anything for a fact this is just an opinion ..

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Old 12-21-2010, 12:56 PM
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3.2 Targa
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Mine does a similar thing when the wipers move from the stopped position. I would describe it as a hiccup.

I think my issue may be a relay based on the hiccup timing.
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Old 12-21-2010, 01:02 PM
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I am pretty sure it was the relay when I fixed this on my 86... around 10 years ago.
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Old 12-21-2010, 01:08 PM
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If they hiccupped on the "ON" mode I would suspect the main switch OR the motor, and if they didnt return home or just stopped wherever the switch was turned off I would look at the motor...

in my case all is well - in fact perfect, just that when using intermittent I am getting the occational STOP mid-wipe (like the power has been cut) then re-starts...They seem to re-start faster if I sweet talk them (yelling only made them stay off lonkger)

The last useful thread RE this issue saw from 2002 so I didnt jump start it as none of the posters were active anymore on this board - Hope to find out and pass along the info

Marc, Relay is other than the rheostat? (sounds cheaper too)?
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Old 12-21-2010, 02:58 PM
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I keep learning stuff...

so I found a part on the wiring diagram says "Right (and left) Heated Spray Jet"
For the wiper washers?

WOW - anyone know how to tell if those work and what temp the water is heated too?

Anyhoe in 85 the circuit is very differant than 86' I will check exactly which I have but it looks like there is something called "wiper intermittant control unit" if that is the issue, its some sort of "black box" - no data shown as to what's going on in there - keep ya posted
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Old 01-29-2011, 01:09 PM
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update:
problem not solved, but I know where the problem is.... its the steering wheel wiper assy.

When the intermittent wipers stop it is due to the control unit not recieving power from the steering wheel switches/assy - if I apply the very lightest presure to the lever, it makes contact and the intermittent wipers are 100% perfect....I checked by wrapping a loosely fitted rubber band between the wiper and cruise levers and the problem is gone... now to replace that thing when time/money permits. (the list is bigger then the wallet, so I have to work them down)
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