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

<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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