Throttle Position Sensor: Testing and Inspection
Throttle Potentiometer, CheckingNOTE: The throttle potentiometer provides information to the Digifant control unit (J 169) for the following functions.
with throttle closed:
- injector shut-off during fuel deceleration cutoff
- idle stabilization
- ignition adjustment during idle using digital idle stabilization function
with throttle partially opened:
- determines injection quantity for acceleration enrichment
with throttle fully opened:
- determines injection quantity during full throttle enrichment
Checking
- connect VAG 1551 Diagnostic tester
- switch ON ignition
- select Function "Read measuring value block"
or
- while observing VAG 1551 display, select the following functions in sequence
1 - Rapid data transfer
01 - Engine electronics
08 - Read measuring value block
- press keys 0 and 5 to select "Display group number 05"
- display will appear as shown
- press 0 key to enter input
- channels will be displayed as shown
- read displayed value in channel 2
- open throttle slowly and uniformly
- displayed value in channel 2 must uniformly increase without interruption
Test A
- disconnect 3-pin throttle potentiometer (G 69) harness connector (arrow A)
- displayed value must be 0.0 >°
- bridge terminals 1 and 2 of the harness connector (arrow 2) using jumpers from VW 1594 adaptor kit
- displayed value must be 90 >° minimum
If YES
- throttle potentiometer control OK
- switch OFF ignition
- replace throttle potentiometer (G 69)
- activate Fault memory and then erase
Vehicles with automatic transmission only:
- after removal/installation or replacement of throttle potentiometer reset control unit to reference setting
If NO
throttle potentiometer control NOT OK
- switch OFF ignition
- check wiring for open circuit or short to control unit positive (+), repair or replace as necessary,
If wiring OK
- replace Digifant control unit (J 169)
- activate Fault memory and then erase