Throttle Position Sensor: Testing and Inspection

Throttle Position Sensor and Accelerator Pedal Position Sensor 2, Checking

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagram

• The Throttle Position (TP) Sensor (G79)/Accelerator Pedal Position Sensor 2 (G185) is located in the accelerator pedal module and communicates the drivers' intensions to the SIMOS Control Module (J361) completely independently of each other. Both sensors are located in the accelerator pedal module and replaced as an entire assembly.

Test requirements

• The fuses for the engine electronics OK.

• The battery voltage must be at least 12.5 Volts.

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

• The parking brake must be applied, otherwise the daytime running lights are switched on.

• On vehicles with an automatic transmission, the selector lever must be in position "P" or "N".

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

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

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

- Remove the left knee bolster.

- Disconnect the electrical harness connector - 2 -.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.





Checking voltage supply

- Switch the ignition on.

- Using a Multimeter, check the following wiring connections for voltage.









- Switch the ignition off.

If the specified values are not obtained:

Checking wiring connections

If the manufacturers test box is being used. Perform the following step.

- Install the Adapter Cable (121 Pin) (VAG1598/31 ).

- Using the Multimeter, check the following wiring connections for open circuit.









Specified value: Wire resistance max 1.5 ohms.

If the specification is not obtained:

- Check the wiring for a short circuit to Battery positive (+) or an open circuit.

- If necessary, repair the faulty wiring connection.

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

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

Assembly is performed in the reverse order of removal, noting the following:

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code, Setting ] Readiness Code, Setting.

End of diagnosis.