tps wiring/voltage check/descrepancy '91 200 20V tq

[benswann at comcast.net]

Bernie,

You may be correct that I am chasing trivia. Also, it is amazing what omitting
a comma will do.  Statement should have said:

No, connector unplugged, not "no connector unplugged"

That is, I tested with the connector unplugged from the TPS.  Harness Connector
needs to be connected to ECU in order to supply voltage through Pin 1,
correct?  From what I gather, 5V feeds via wire/pin 1 and returns to ECU via
pin 3 (similarly with pin 2).  Pin 1&2 register a full 5V.  Pin 1&3 don't.
Continuity test shows wires for 1&3 when combined/looped back, round-circuit
show almost 0 resistance.  Probably should run separate wire to answer
everyones scepticism about the wires, including my own.  For the moment we are
working on verifiable assumption.

I must conclude at this time that 1) wires are good, although no harm in double
checking.  2) either ECU is bad (internal problem) or Bentley spec. is off.  So
far 3 out of 3 cars that I have information on have this problem, which is why
I am wondering if Bentley gives the fully correct procedure.

I don't have the special VAG harnesses used, but beleive I have been deducing
the correct wires to analyze.   I am pretty sure I have been doing my test
properly.  Most of what I have been replying back on is that folks did not read
my original email throroughly and later answers back to well meaning replies
result in further confusion such as yours.  Anyway, assume I have been
following the procedure per. Bentley.  and assume wiring is good.  What then
does the low voltage mean?

What does your voltage between pins 1&3 read?

Maybe this is trivia, but I have not found/fixed the problem yet.  I am sure
there is a problem and I will get to the bottom of it eventually.  Yes to some
degree DFI-IAB and leave well-enough alone, but when a second and/or third
component malfunctions later on, troubleshooting gets compounded.

Thanks,

Ben
> Ben,
>
> IMO, you are persistant in your persuit of trivia.
>
> > From: benswann at comcast.net
> >
> > No connector unplugged - as per Bentley.
> Not per Bentley, if you are following inst. on pg 24-130-1 for the
> measurement of V between #1 and #3.  The connector is to be unplugged from
> the TP for this as well as the supply voltage (#1 and #2) measurement.  I
> have not measured mine, but this (#3) is an ECU input signal, and therefore
> is a trivial (high impedence) measaurement without the TP connected.  Assume
> Bentley is wrong again in this instance.
>
> Of greater import are the TP resistance measurements. If you refer to the
> schematic, pg 542, you see that the TP has a fixed resistor on either side
> of the tapped pot resistor, so the operating voltage at #3 can never be as
> large as is the V on #2, relative to the supply, #1.  If your R values check
> out and the pot gives a smooth change in R, don't sweat it, look elsewhere
> for your problem.
>
> Bernie
> >
> > Ben
> >> Did you have the connector plugged in when checking the voltage?
> >> Commonly there is a series resistor on the 5v line to protect the ECU.
> >> I'll almost bet that you're supposed to unplug the TPS when checking
> >> this voltage.
> >>
> >>
> >> On Wednesday, September 10, 2003, at 02:41  PM, benswann at comcast.net
> >> wrote:
> >>
> >>> Gary,
> >>>
> >>> Thanks a lot for checking.  It seems like there is quite some
> >>> variation in the
> >>> readings.  Anyone else checked theirs.  Two cars I've checked have
> >>> voltage
> >>> around 3.5V.
> >>>
> >>> Bently says voltage between pins 1 and 3 on TPS connector should be
> >>> 5V.  If not
> >>> then bad wiring or ECU.  Assuming I have correctly checked my wiring,
> >>> then what
> >>> causes this variation.
> >>>
> >>> Note:  Wiring diagram indictes a straight thru connection between TPS
> >>> and ECU
> >>> on Pin 3m, so really not much else there to test.
> >>>
> >>> Ben
> >>>
> >>> [From: "motogo1" <motogo1 at cox.net>
> >>> To: "Audi 200" <200q20v at audifans.com>
> >>> Subject: Re: Throttle position sensor/circuitry checking w/resp. to
> >>> poor fuel
> >>> econ.
> >>> Date: Tue, 9 Sep 2003 23:19:47 -0700
> >>>
> >>> Well, on my TPS, voltage between pins 1 and 2 is 5V..in spec per
> >>> Bentley.
> >>> Between pins 1 and 3, 1.6 volts. Not even close to Bentley spec. My
> >>> car is
> >>> chipped with IA III+ and runs strong, with no problems. I'm going to
> >>> have to
> >>> check the mileage, to see what I'm getting.
> >>>
> >>> Gary Martin
> >>> 94 UrS4
> >>> 91 200 TQA]
> >>
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> > 200q20v at audifans.com
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>