From: David R. Hendrickson [riffraff@eskimo.com]
Sent: Thursday, April 11, 2002 5:59 AM
To: 928
Subject: [928] Programmable wiper delay mod

After buying my car a year and a half ago, I knew fairly quickly that I
didn't really like the way the intermittent wiper delay worked:   taking
one hand off the steering wheel, having to fumble under the pod looking for
the wheel to adjust the delay and being distracted from the task at hand (
driving ).  So after thinking about it since I bought the car and a recent
discussion over on the web board, I decided to look into it a bit more.

Along with my S4, I also own a 96 VW Jetta.  I've been into VW's since I
was 15 ( 20 years ).

The intermittent wiper on the VW is a fixed ~10 seconds.  There is an
optional wiper relay that a VW can use, one that allows you to program the
delay between 3 and 30 seconds, from the stalk.  After studying the VW and
Porsche wire schematics, the wiper systems on both cars are wired almost
exactly the same.  When you engage the intermittent wiper, Pin "J" on the
wiper switch goes to the potentiometer and on to pin "I" on the wiper
relay.  The variable-resistance side of the potentiometer then goes to pin
"R" on the relay, giving it a delay value.  While there are 7 pins on the
Porsche relay, there are only 6 on the VW relay, exactly the same as the
Porsche relay, except it's missing the "R" input.

So tonight I decided to install my VW factory fixed delay relay.  It works
exactly like it does in the Jetta, fixed 10 sec. delay.  Because the "R"
pin is missing from the relay, the pod potentiometer circuit is totally
bypassed.  (on my car, the pod pot changed the delay from 5 to 15 seconds )

I removed the fixed relay and installed my programmable delay relay from my
Jetta.  Again, it works exactly like it does in the Jetta.  This relay has
an IC in it and here's how it works.  You turn on the intermittent wiper
and let it wipe once, then turn the wiper off ( you can turn it off while
it's wiping too ).  Wait the amount of time you want between wipes ( 3-30
seconds ) and then go to intermittent again.  The wipers will wipe and
continue to do so at this setting until you turn them off.  Everything else
works normally.  From the wire diagrams, it looks like this should work an
any year 928.

Again, you do this with your fingers, no taking your hand off the wheel to
adjust the delay pot.

The VW part number for this relay is 1HM 955 531 B.  I got mine used for
$40, not sure how much at the dealer.

Now all I have to do is buy another oneŠ


dave

David R. Hendrickson
'88 S4 AT Silver Metallic
Kent, WA