[T3] Hella Intermittent Wiper Add-on # 5WA 001 871-041 12V

[Will McCreight <whmcc@attglobal.net>]

<x-flowed>Just picked up a $50 or so "Screen Wiper Intermittent Control Unit", or 
"Wischer-Intervallschalter" in the native VW tongue, made by Hella under 
the Unit number given above.  I have grave difficulty with wipers like 
metronomes when unnecessary... a pet peeve of mine.

However, even though I've blown four fuses, tried several methods of 
wiring it into the switch, etc., I cannot get it to do anything except 
"relay" stop the wiper in its tracks on the windshield for about a 
second, then it clicks open again, and the wiper continues until the 
interval passes again, then the hiccup on the screen again...no park, no 
delay, just aggrevation on my part.  Wondering if this is meant to work 
with my 1970 SQ FI.

I've been using page 49B as the wiring schemata for my T3 for reference, 
and indeed, 6 spade connectors, a black/violet (53a), black/yellow 
(53b), a brown ground in and out (31 and 31b), as well as two blacks (30 
and 53) have been identified on the wiper switch back.

Hella's instructions show two diagrams, depending on whether (1) 
positively connected wiper motor, or (2) negatively connected wiper 
motor.  I have tried both by now.

Their written instructions include "switch on ignition, connect one 
terminal of the test lamp to earth...with the wiper motor switched OFF, 
check ALL terminals of the wiper switch, observing whether the test lamp 
lights up with MORE than ONE terminal (if so, one terminal of the test 
lamp should be connected to a positive (battery or fuse) instead of 
earth before carrying out the following steps, as the wiper switch is 
NEGATIVELY connected to the wiper motor."

The next steps..."run wiper at highest speed and check all terminals of 
wiper switch with the test lamp, and observe which terminal causes the 
test lamp to light up with the brightest steady light.  Switch off the 
wiper motor...the test lamp MUST go out once the wiper motor has reached 
the "parked" position.  Cut the lead connected to the terminal 
determined above...the wiper should now no longer function at low speed."

They then go on to describe the wiring into the leads from the socket 
into which their relay module with potentiometer is to be inserted, and 
the two different methods are spelled out, based again on "positively or 
negatively connected wiper motor" diagrams.

The last paragraph may be the kicker..."If, during the test, the lamp 
flashes SHORT ON and LONG OFF with ONE of the terminals, the wiper motor 
is not suitable for connection to the screen-wiper intermittent control 
unit."

My testing has shown that I have two hot positives coming into this 
switch (30 & 53) when tested against earth with the test lamp, ignition 
on.  Is this a "negatively connected motor"?
When then wired up properly as such, with the relay interposed on 53 per 
their instructions, I get no effect on wiper motor, despite rhythmic 
interval relay action.  However, when wiper switch is turned off, relay 
"chatters" very quickly.

When instead, wired for "positively connected motor", I get the one 
second pause mentioned at the top, as though the interval relay kick 
stops the power, but no park, and wipers then continue from wherever 
they've stopped until the next interval stutter/stop.

As far as their "short on/long off" disclaimer, line 53 at highest speed 
does act this way, as though there is a big power draw by the motor as 
it travels across, then a brief lowering of draw (during which the lamp 
glows brighter) as the wipers change direction.

I have therefore concluded that this is likely not going to work out, 
and I am feeling discouraged, stumped, and aggrevated.  Any thoughts?  
Have others succeeded at this (is it just me?), or is the T3 just not 
capable of allowing intermittentcy of wiperage?  Would a different wiper 
switch/motor/or wiring pattern allow for success, either with this Hella 
Intervallschalter, or some other unit?

I am a real RainX addict, and prefer to have rain sheet itself off of 
the windscreen rather than be metronomed to death--and we all know that 
it rains SOMETIMES here in P'town!


--
Will McCreight
whmcc@attglobal.net
Portland, OR
(208) 661-6262 cell

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