Throttle Position Sensor: Testing and Inspection

Diagnostic Procedures




Throttle Position Sensor, Checking

Both Throttle Position (TP) Sensor (G79) and Accelerator Pedal Position Sensor 2 (G185) are located at the accelerator pedal and communicate the driver's intentions to the ECMs completely independently of each other. Both sensors are integrated into one housing.

• Observe safety precautions => [ Safety Precautions ] Safety Precautions.

• Observe rules for cleanliness => [ Clean Working Conditions ] Clean Working Conditions.

• When servicing terminals in the harness connector for the Intake Air Temperature (IAT) sensor, use only gold-plated terminals.

Special tools, testers and auxiliary items required

• Hand multimeter (V.A.G 1526) or Multimeter (V.A.G 1715)

• Test adapter kit (V.A.G 1594)

• Wiring diagram

• Battery voltage (both batteries) must be at least 11.5 Volts.

• All electrical consumers such as, lights and rear window defroster must be switched off.

• Parking brake must be engaged.

• For vehicles with automatic transmission, selector lever must be in " P".

• If the vehicle is equipped with an A/C system, this must be switched off.

• The Ground (GND) connections between engine and body must be OK.

• Fuses in right instrument panel fuse holder must be OK:

Right instrument panel fuse holder





Test Sequence

- Remove cover in footwell (driver side).

- Disconnect 6-pin connector from Throttle Position (TP) Sensor.

- Switch ignition on.

Checking voltage supply

- Connect multimeter to the following connector terminals for voltage measurement.

- Terminal 1 + Ground

- Terminal 1 +5

- Terminal 2 + Ground

- Terminal 2 + 3

- Specified values: at least 4.5 V





- Switch ignition off.

If specifications are not obtained:

- Check wires to control module according to wiring diagram.

Check wires to control module

- Connect test box to Engine Control Module (ECM) 2 (J623) wiring harness on connecting test box for wiring test.

- Check wires between test box and 6-pin connector for open circuit according to wiring diagram.

- Terminal 1+Socket 72

- Terminal 2+Socket 73

- Terminal 3+Socket 36

- Terminal 4+Socket 35

- Terminal 5+Socket 33

- Terminal 6+Socket 34

- Wiring resistance: max. 1.5 ohms





- Check wires for short circuit to each other, to vehicle Ground (GND) and to B+. Specification: infinite ohms

- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace Throttle Position sensor.

- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09, Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.