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Windshield Sprayer System - No power to pump?

 
Old 02-26-2018, 11:35 PM
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Question Windshield Sprayer System - No power to pump?

Hey everyone. Somehow cleaning out the sunroof drains on my '85 lead to me dismantling and cleaning out the non-functioning windshield sprayer system. After disassembly I realized it had the classic failure, completely clogged with rust. I cleaned everything and got out that rusty gunk, then bench tested the 12V sprayer pump and it spun freely. I mounted everything back up, filled the reservoir with some water, then tested the sprayer from the steering column switch... nothing happened. Got out the multimeter and put it to the leads for the pump, pulled the column switch again, and found it's getting no power. Checked the fuses, all good there.

Not entirely sure what to check next, so any ideas on where to go from here?

And here's some inspiration to those of you yet to do this job
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Old 02-27-2018, 12:34 AM
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thats pretty rusty,
did you remove the metal collars inside the tank inlet and the fill tube outlet?
if not you should .
go easy on the hose clamps.
What year is you car?
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Old 02-27-2018, 12:42 AM
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Originally Posted by Mrmerlin View Post
thats pretty rusty,
did you remove the metal collars inside the tank inlet and the fill tube outlet?
if not you should .
go easy on the hose clamps.
What year is you car?
I did remove what was left of them. Both ends were literally clogged water tight with 3 solid inches of rust. The car is an '85 automatic.
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Old 02-27-2018, 09:04 AM
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post a picture of the CE panel maybe one of the washer relays is missing or bad ,
you have two relays for the washers,
one for the headlamps and one for intensive washers.
I dont have my wire diagram handy to see how the washer pump wires might interconnect.
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Old 02-27-2018, 11:08 AM
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bad relay, bad wire, or bad switch. do you have the WSM?
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Old 02-27-2018, 11:33 AM
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Originally Posted by Mrmerlin View Post
post a picture of the CE panel maybe one of the washer relays is missing or bad ,
you have two relays for the washers,
one for the headlamps and one for intensive washers.
I dont have my wire diagram handy to see how the washer pump wires might interconnect.
I'll snap a picture tonight of the panel.

Originally Posted by Ducman82 View Post
bad relay, bad wire, or bad switch. do you have the WSM?
I have a PDF copy of the WSM but it's unfortunately incomplete and doesn't cover this section. Still looking for a complete one for an '85.
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Old 02-27-2018, 07:27 PM
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Here's the panel:

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Old 02-28-2018, 07:12 PM
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Unrelated to the washer fluid pump, but looking at VIII (middle row, fourth relay from the left) the chart shows it should be a defroster. As far as I can tell my defroster works, but could this fuse tester be out of place?
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Old 03-02-2018, 12:54 AM
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Found a deal on a relay tester so I'll be pulling them and testing this weekend. I checked the relay part numbers and it appears to have the correct ones installed for the wiper system.

So here's my current understanding of the system; is this correct?
  • Pull lever towards you - standard windshield sprayer operation & wipers wipe three or so times.
  • Push lever away from you - standard headlight sprayer (only sprays if lights are on/up).
  • Push small black button on the bottom of dash pod - intensive sprayer for headlights if on/up. System does not continue to spray if button is held & only supplies momentary power to intensive pump.
  • Intensive sprayer only applies to headlights and not the windshield.
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Old 03-02-2018, 10:59 AM
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Intensive washers apply to windshield only not headlights - also triggers 3 wipes.

Your relay tester will test only standard SPST/SPDT relays - you have more relays that aren't standard SPST*, its cheaper to just replace these with new ones than to test them.

The fuse tester relay is just a standard relay with a fuse tester in parallel - it can go in any slot that takes a standard SPST ('53 type) relay.

Alan

* a 928 uses no standard SPDT relays
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Old 03-02-2018, 11:23 AM
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Originally Posted by Alan View Post
Intensive washers apply to windshield only not headlights - also triggers 3 wipes.

Your relay tester will test only standard SPST/SPDT relays - you have more relays that aren't standard SPST*, its cheaper to just replace these with new ones than to test them.

The fuse tester relay is just a standard relay with a fuse tester in parallel - it can go in any slot that takes a standard SPST ('53 type) relay.

Alan

* a 928 uses no standard SPDT relays
Gotcha. Thanks for the clarification, Alan. So knowing that now, I tested the intensive button and got nothing - no wipes, no sprayer. I'm going to check that the button is making contact next.

I admit I'm no expert on relays, does this mean that any standard SPDT relay will work in place of Porsche part #'s? Those things are pricey!
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Old 03-02-2018, 09:01 PM
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You have a relay for the intensive wash (IX) and a different relay for the intermittent wipers (VII). The intensive wash switch operates the intensive wash relay that operates the pump. The intermittent relay is responsible for the 3 wipes mode (for either wash type) and also for the wiper parking. Both wash mode triggers go though the intensive relay too. Sounds like you get the 3 wipes on regular washing. Both relays run off Fuse 5 so if intermittent works the intensive should too. Check the switch first ...

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Old 03-04-2018, 11:44 PM
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Good evening fellas. I spent the afternoon digging into this and also cleaned up the corrosion on the 14 pin connector in the engine bay while I was at it. It wasn't too bad for probably never being touched before; I was surprised.

Anyway, switches for the wiper system all appear to be making proper contact. My relay tester arrived and it's a pretty handy device, but limited to 4 or 5 pin relays. I tested it on a known bad relay from my junk drawer first and it tested bad, then a know good and tested good. So I proceeded to check all the 5 pin relays in the 928

Relay XIX for the headlamp washer tested bad. I couldn't test relay IX for the intensive washer because it's a strange 6 pin style, but I do not hear it "click" on and off when the intensive button is pressed. I do hear a click when I pull the column switch towards me for standard wiper sprayer, but I assume this is just the VII relay engaging for the three wiper wipes.

Do any of you know a way for me to bench test relay IX? The schematic looks somewhat complicated.
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