Throttle Position Sensor: Testing and Inspection

Throttle Position (TP) sensor -G79- and Sender 2 for accelerator pedal position - G185-, checking

Both the Throttle Position (TP) sensors -G79- and the Sender 2 for accelerator position -G185- are located on the accelerator pedal and independently signal the driver's requirements to the engine control module. Both are located in one housing.

- Connect vehicle diagnostic, testing and information system VAS 5051 or V.A.G 1551 Scan Tool and select engine electronics control module with "Address word" 01. For this purpose, ignition must be switched on.

Indicated on display


Rapid data transfer HELP
Select function XX


- Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.

Indicated on display


Reading measured value block Q
Enter display group number XXX


- Press keys 0, 6 and 2 for "display group number 62" and confirm entry with Q key.

Indicated on display


Read measured value block 62
1 2 3 4


- Check specifications for electronic throttle potentiometer voltages.

Display Group 62:

- Observe readouts in display zones 3 and 4.
- Slowly depress accelerator pedal.

Percentage displayed in zone 3 should rise evenly. Tolerance range from 12...92% is not fully utilized.

Percentage displayed in zone 4 should also rise evenly. Tolerance range from 4...49% is not fully utilized.

NOTE: The value displayed in zone 3 must always be about twice as large as that in zone 4.

If the displays are not as described:
- Check voltage supply and wiring for TP sensor/Sender 2 for accelerator pedal position.
- Adjust TP sensor/Sender 2 for accelerator pedal position.

Checking voltage supply for TP sensor/Sender 2 for accelerator pedal position

- Remove driver's storage compartment/trim.
- Disconnect connector for TP sensor/Sender 2 for accelerator pedal position.

NOTE: The connector is clipped onto the pedal bracket near the brake light switch.

- Switch ignition on.
- Connect hand-held multimeter (voltage range) between following sockets on connector:

Vehicles up to model year 2001:

6-pin connector on
wiring harness, socket Specified value

2 + Ground approx. 5 V
2 + 3 Happrox. 5 V
5 + Ground approx. 5 V
5 + 4 approx. 5 V

Vehicles from model year 2002:

6-pin connector on
wiring harness, socket Specified value

2 + Ground approx. 5 V
4 + 3 approx. 5 V
5 + Ground approx. 5 V
6 + 4 approx. 5 V

If specifications are attained:
- Additionally check signal wires .

If the specified values are not obtained:
- Check wiring between engine control module and TP sensor/Sender 2 for accelerator pedal position.

Checking signal wiring and wiring connections between TP sensor/Sender 2 for accelerator pedal position and engine control module

- Connect test box VAG 1598/31 to wiring harness for engine control module; do not connect engine control module. Connecting VAG 1598/31 Test Box
- Check for open circuit and short to positive or Ground in following wiring connections:

Vehicles up to model year 2001:

Connector Socket Test box VAG 1598/31 Socket

1(signal wire) 35
2 73
3 36
4 33
5 72
6(signal wire) 34

Vehicles from model year 2002:

Connector Socket Test box VAG 1598/31 Socket

1 72
2 73
3 36
4(signal wire) 35
5 33
6(signal wire) 34

Wire resistance: max. 1.5 Ohm

- Correct any open/short circuit as necessary.

If no wiring malfunction is detected:
- Replace TP sensor/Sender 2 for accelerator pedal position.