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

On 2 Apr 2006 at 19:23, Will McCreight wrote:

> 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'm sure this can be made to work, but I've never done it. I'm not 
that familiar with the circuit, and even looking at the wiring 
diagram doesn't seem to help much. I think I may be able to help a 
bit, however.

> 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.
I believe they are asking whether the switch is wired on the ground  
side (-) or hot side (+) of the wiper motor. (For a postive ground 
car, these signs would be reversed.)

If the unit has any solid state devices in it, you've probably blown 
them up by connecting them both ways. This might explain why it 
doesn't work 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."

Here I think they are just trying to help you figure out which way it 
is wired. If I'm right about what they mean, our cars are 
"positively" connected. Theirs is a very awkward description.

> 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."

This is confusing to me, but maybe they know what they're doing.

> 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."

This sounds like a description of a wiper control which ALREADY has 
intermittent control.

> 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"?

No, I think this is a positive connected motor.

Sorry, but I don't think I'm any help past this point.

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

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