[T3] Throttle Valve Switch

[Jim Adney]

On 8 Nov 2013 at 13:16, Dennis Stiefel wrote:

> The car only has 77K miles
> on it when the lady who drove it thrown a rod in 1980 due to lack of oil.
> Can they wear out with that few of miles?   

That seems rather low mileage. Go ahead and remove it from the car (2 
screws, then pull) and pop the cover off. There are some delicate 
parts inside, but you can go ahead and clean the contact track 
carefully. Just don't bend anything.

Use my faq to adjust it when you put it back on, or check it with an 
Ohmmeter when you've got it apart. The thing that goes wrong with 
them is that they get worn in the contact track such that one of the 
moving contacts can short between 2 of the interlocking contact 
fingers (you'll see them when you open it up.) The brain expects 
contact with only 1 at a time, so contacting 2 at once "confuses" it, 
and the FI shuts off. Thus the miss.

This could happen with any of the '70-3 TVSs, but I've only ever seen 
it in the '72-3 version. I don't know why the '70-1 versions seem to 
be sturdier, but replacements for the '72-3 version have different 
(better) internal construction.  

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