Throttle Position Sensor Checking

The Throttle Position sensor G79 is located on the accelerator pedal and transfers Throttle Position information to the Engine Control Module.

Special Tools, Testers And Auxiliary Items:
- VAG 1551/1552 Scan Tool with VAG 1551/3 adaptor cable
- VAG 1598/22 Test Box
- VW 1594 adaptor kit
- VAG 1527B LED tester
- Wiring diagram

Test Sequence:
- Connect VAG 1551/1552 Scan Tool
- Switch ON ignition
- Press 0 and 1 buttons to select address word 01 "engine electronics"
Display will appear as shown:

Rapid data transfer HELP
Select function XX

- Press 0 and 8 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 XX

- Press 0 and 2 buttons to select "display group 2"
- Press Q button to enter input
- Observe value in display field 2 (accelerator pedal position)
Display will appear as shown:

Read measuring value block 2 ->
rpm 0.0% 0 1 0 18.4°C

Specification: 0.0 % (accelerator pedal not operated)

- Observe value in display field 3
Display will appear as shown:

Read measuring value block 2 ->
rpm 0.0% 0 1 0 18.4°C

Specification:
0 1 0 (accelerator pedal not operated)
0 0 0 (accelerator pedal operated)

- Press accelerator pedal down slowly, display field 2 must increase steadily to 100 % (accelerator pedal fully depressed)
Display will appear as shown:

Read measuring value block 2 ->
rpm 100.0% 0 1 0 18.4°C

NOTE for vehicles with automatic transmission ONLY: The kickdown switch pressure point must be distinctly felt BEFORE the Wide Open Throttle stop position is reached.

If specified end value not reached:
- Adjust Throttle Position sensor

If display value does not change or is irregular:
- Check Throttle Position sensor G79 as follows:
- Switch OFF ignition
- Disconnect Throttle Position sensor harness connector
- Switch Fluke 83 multimeter to resistance range





- Measure resistance between sensor terminals 1 and 3 using jumper wires from VW 1594 adaptor kit:
Accelerator not depressed: Closed Throttle position
Specification: 1000 to 1500 Ohms.
Accelerator depressed: Wide Open Throttle position
Specification: 1500 to 2500 Ohms.

If specifications not obtained:
- Replace Throttle Position sensor G79
- Display the readiness code

If DTC memory was erased:
- Create readiness code again

If specifications obtained:
- Switch OFF ignition
- Disconnect Throttle Position sensor harness connector





- Connect VAG 1598/18 Test Box to ECM harness connector





- Check following wiring connections for: Open circuits and/or Short to positive or negative:
Wiring from connector terminal 1 to Test Box socket 15
Wiring from connector terminal 2 to Test Box socket 57
Wiring from connector terminal 3 to Test Box socket 55
Wiring from connector terminal 4 to Test Box socket 65
Wiring from connector terminal 5 to Test Box socket 62
Wiring from connector terminal 6 to Test Box socket 33
- Repair any open/short circuit as necessary

If neither an open or short circuit exists:
- Replace Diesel direct injection system ECM
- Display the readiness code

If DTC memory was erased:
- Create readiness code again