tps wiring/voltage check/descrepancy '91 200 20V tq
b.benz at charter.net
Wed Sep 10 21:32:12 EDT 2003
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.
>> 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
>>> 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
>>> 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.
>>> [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
>>> Date: Tue, 9 Sep 2003 23:19:47 -0700
>>> Well, on my TPS, voltage between pins 1 and 2 is 5V..in spec per
>>> 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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