quattro Digest, Vol 139, Issue 3

Wed May 6 17:05:49 PDT 2015

There are two micro switches made by hitachi. They are very reliable and unlikely to be at fault. The wiring to them is more likely culprit. 
Each switch has two wires. They then joint in the 3 wire plug at the top. As the other poster said they use common earth. 
To check them you don't really need to check ohms etc. they are either reading continuity, or not..that's signal they send to Ecu
A full breakdown of the checking procedure can be found at t85q.com.  Look for original Quattro manual which is all there in electronic format and its same for yours .

In short, one is closed till throttle body reaches about 20 degrees. As throttle moves it then registers as open. The next one is open until throttle reaches near wide open then it closes. 

If you move throttle plate manually with engine off its easy to hear them click. 

Regards. Paul 

Sent from my iPad

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> Today's Topics:
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>   1. Throttle position sensors on a 1987 Audi 4000 Quattro
>      (dvanden46 at gmail.com)
>   2. Re: Throttle position sensors on a 1987 Audi 4000 Quattro
>      (Huw Powell)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 5 May 2015 21:25:47 +0000
> From: <dvanden46 at gmail.com>
> To: "=?utf-8?Q?quattro at audifans.com?=" <quattro at audifans.com>
> Subject: Throttle position sensors on a 1987 Audi 4000 Quattro
> Message-ID: <55494833.c5b3340a.49e3.024c at mx.google.com>
> Content-Type: text/plain; charset="utf-8"
> 
> 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.
> 
> 
> 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.
> 
> 
> Sincerely,
> 
> 
> David Vanden
> 
> 
> 
> 
> 
> 
> Sent from Windows Mail
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> ------------------------------
> 
> Message: 2
> Date: Tue, 05 May 2015 19:37:14 -0400
> From: Huw Powell <audi at humanspeakers.com>
> To: quattro at audifans.com
> Subject: Re: Throttle position sensors on a 1987 Audi 4000 Quattro
> Message-ID: <5549542A.9040600 at humanspeakers.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
> 
> 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.
>> 
>> 
>> 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.
>> 
>> 
>> Sincerely,
>> 
>> 
>> David Vanden
>> 
>> 
>> 
>> 
>> 
>> 
>> Sent from Windows Mail
>> 
>> ---
>> This email has been checked for viruses by Avast antivirus software.
>> http://www.avast.com
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> End of quattro Digest, Vol 139, Issue 3
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