Throttle position sensors on a 1987 Audi 4000 Quattro

[Huw Powell]

The red and black don't matter, since you are just testing a pair of 
switches.

The readings should be open (infinite or no reading) or zero.

The idle switch is under the throttle body and the WOT switch is on the 
top (so you can trigger it manually).

I forget which terminal is the "common" one, but it's probably the 
center one.

Measuring from the common terminal to idle should be zero with the 
throttle closed, and open with it cracked even a bit.  With the engine 
off you might even be able to hear the switch actuate.

Common to WOT should be open until the lever switch on top of the 
throttle body is closed by the moving metal bit that actuates it, then 
it should be closed.

20 ohms is a dirty switch, or inaccurate meter, or low batteries, or all 
three.

The assembly - two switches with wires going to one connector - used to 
be a dealer part, I paid 62.50 for one back in July 2000.  The idle 
switch is a bit fidgety to install and adjust.

- Huw

On 5/5/2015 5:25 PM, dvanden46 at gmail.com wrote:
> Does anyone know the correct way to check the throttle position sensors on the throttle body of a 1987 Audi 4000 Quattro?  If someone could tell me the specifics I would appreciate it.  I think I did it right using a multi meter but I am unsure.  I set it to ohms and I checked the resistance by placing the red probe on the outside contact of the plug and the black probe on the middle one. This was with the throttle at idle. There was no reading.  Likewise there was no reading when I placed the red probe on the inside contact and the black probe on the middle contact.  I believe they were both supposed to read zero under the circumstances.
>
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> With the throttle open and the full throttle switch activated I got a reading in the 20’s or something for the full throttle switch, but I believe it was supposed to be zero.  All this makes me think that the sensors are duds.  But, if someone could confirm how to properly test and what are correct readings I would appreciate it.  Also, if anyone has found micro switches that can be used to replace the faulty ones (assuming they are faulty) so I don’t have to buy another throttle body, please tell me where they can be gotten.
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> Sincerely,
>
>
> David Vanden
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