With Manufacturer's Scan Tool
Throttle Position (TP) Sensor -G79- Checking
Throttle Position (TP) sensor -G79- is located on accelerator pedal and communicates physical pedal position to Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM).
Special tools
- VAG 1551/1552 Scan Tool with VAG 1551/3 Adapter cable
- VAG 1598/22 Test Box (MY 1999)
- VAG 1598/31 Test Box (from MY 2000)
- Fluke 83 multimeter, or equivalent
- VW 1594 Adapter kit
Test sequence
- Switch ON ignition but do not start engine.
- Press 0 and 1 buttons to select Address word 01: "Engine electronics"
Display will appear as shown (example only)
038906018M 1.9l R4 EDC 00AG 1813 ->
Coding 0001 WSC XXXXX
- Press -> button.
Display will appear as shown
Rapid data transfer HELP
Select function XX
- Press 0 and buttons to select Function 08:"Read measuring value block".
- Press Q button to enter input.
Display will appear as shown
Read measuring value block HELP
Input Display group number XXX
- Press 0, 0 and 2 buttons to select "Display group 2".
- Press Q button to enter input.
- Observe value in Display zone 2 (Throttle Position).
Specification: 0.0 % (pedal not operated)
Read measuring value block 2 ->
0 rpm 0.0% 0 1 0 18.4 5C
- Observe value in Display zone 3.
Specification:
0 1 0 (pedal not operated)
0 0 0 (pedal operated)
Read measuring value block 2 ->
0 rpm 0.0% 0 1 0 18.4 5C
- Press accelerator pedal down slowly.
Specification: value in zone 2 must increase steadily up to 100 % (pedal fully depressed).
Read measuring value block 2 ->
0 rpm 100.0% 0 0 0 18.4 5C
On vehicles with an automatic transmission, the kickdown switch pressure point must be distinctly felt before the Wide Open Throttle stop position is reached.
If specified end value not reached
- Replace Throttle Position sensor -G79-
If display does not change or is irregular
- Check Throttle Position sensor as follows:
- Switch OFF ignition.
- Disconnect harness connector for sensor.
- Connect VAG 1598/22 (or 1598/31) Test Box to ECM wiring harness.
Check following combinations for open circuits and/or short to positive or negative:
- Wiring between connector terminal 1 and Test Box socket 8.
- Wiring between connector terminal 2 and Test Box socket 11.
- Wiring between connector terminal 3 and Test Box socket 23.
- Wiring between connector terminal 4 and Test Box socket 24.
- Wiring between connector terminal 5 and Test Box socket 12.
- Wiring between connector terminal 6 and Test Box socket 25.
- Correct any open/short circuit as required.
If neither open nor short circuit exists
- Replace Engine Control Module J248.
- Display the Readiness code. Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Displaying Readiness Code" Testing and Inspection
If DTC memory was erased
- Set the Readiness code. Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Setting Readiness Code" Testing and Inspection