Throttle Position Sensor: Testing and Inspection

Throttle Position Sensor from MY 1999/Closed Throttle Position Switch, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram

Test requirement

• The Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) 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 ).

Test procedure

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

Start diagnosis

- Remove the engine cover.

Checking internal resistance

- Disconnect the Throttle Position (TP) Sensor ( G79) electrical harness connector.

- Using a multimeter, check the Throttle Position (TP) Sensor (G79)/Closed Throttle Position (CTP) Switch (F60) terminals 1 to 3 for resistance.





Specified value: 1000 to 1500 ohms

- Depress the accelerator pedal.

Specified value: 1000 to 2500 ohms

If either specification was not obtained:

- Replace the Throttle Position (TP) Sensor (G79 ).

If the specifications were obtained:

Checking wiring

- Install the test box. Refer to => [ 68 Pin Test Box Adapter, Installing ] 68 Pin Test Box Adapter, Installing.

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

- Remove the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a Multimeter, check the Throttle Position (TP) Sensor (G79) electrical harness connector terminals to the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) electrical connector for an open circuit.









Specified value: 1 ohms max.

If the specification is not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

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

- If necessary, repair the faulty wiring connection.

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

- Replace the Throttle Position (TP) Sensor (G79 )/Closed Throttle Position (CTP) Switch (F60).

- 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 not OK:

- Replace the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

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 ] Readiness Code.

End diagnosis.