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Re: [T3] Mystery Wire


On 6 Aug 98, at 17:10, wcollins@sbnsw.com.au wrote:

> I've been foolin' with my '72 Notch.  Under the back seat at the battery there 
> are the two wires which go to the positive and negative terminals.  No 
> problem.  Then there are two wires one of which is brown and the other is 
> brown and white.  Both, (according to my '73 Squareback, Carbed) are earthed, 
> one to the battery (-) and the other to the negative lead on the metal plate 
> under the back seat.  Effectively both are to earth.  No problem either.

 ALL these small wires are part of the computer diagnosis system that 
VW introduced in the last month of the 71 model year.  There are two 
ground wires, one on each end of the battery ground strap.  Using the 
ground strap as a shunt, this system could measure the current draw 
of the starter while cranking the engine.  I believe the system could 
estimate the compression of each cylinder based on the current 
required to crank up to TDC for each.

> Now for the mystery wire.  On both cars it has been cut. It's Red and Yellow.  
> But what is it for.  My Notch obviously doesn't need it and my wagon has been 
> running fine without it, but I don't have a current diagram which mentions it. 

I believe all these are shown in the schematics in the Bentley 
manual.  This last wire went to a water level sensor in the top of 
the special battery that came with the car.  These batteries have not 
been available for 20 years.  Your car will run just fine without it.

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

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