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

Test requirement

• The Motronic Engine Control Module (ECM) (J623) fuses OK.

• Battery voltage at least 12.5 volts.

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

• Vehicles with automatic transmission, shift selector lever into position "P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Use only gold-plated terminals when servicing the electrical harness connector terminals in Throttle Position (TP) Sensor (G79)/Accelerator Pedal Position Sensor 2 (G185).

Test procedure

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

Start diagnosis

- Disconnect the Throttle Position (TP) Sensor (G79)/Accelerator Pedal Position Sensor 2 (G185) electrical harness connector - 2 -.





Checking voltage supply and wiring

- Switch the ignition on.

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










- Switch the ignition off.

If the specification is not obtained:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box.

If the manufacturers test box is not being used, perform the following step.

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

- Using a Multimeter, check the Throttle Position (TP) Sensor (G79)/Accelerator Pedal Position Sensor 2 (G185) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J623) electrical connector T94 for resistance.






Specified value: 1.5 ohms.

If the specification was not obtained:

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

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

- If necessary, repair the wiring connection.

If the specification was obtained:

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

- 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 returns and no malfunction is found in the wiring and voltage supply was OK:

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

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

Final procedures

After 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 ] Clearing Diagnostic Trouble Codes.

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