Throttle Position Sensor: Testing and Inspection

Throttle Position Sensor G79 And Accelerator Pedal Position Sensor 2 G185, 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.
- Ignition off

Test procedure
- Perform a preliminary check to verify the customers complaint. Preliminary Check

Start diagnosis

NOTE: 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 sequence
- Remove the steering column cover.
- Disconnect the Throttle Position (TP) Sensor G79 / Accelerator Pedal Position Sensor 2 G185 electrical harness connector.

Checking voltage supply and wiring
- Switch the ignition on.







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

Throttle Position (TP) Sensor Specified value
G79 / OR Kick Down Switch/Closed
Throttle Position Sw G185, checking
1 to Ground (GND) about 5 V
1 to 5 about 5 V
2 to Ground (GND) about 5 V
2 to 3 about 5 V

- 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







- 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.

Throttle Position (TP) Sensor Motronic Engine Control Module
G79/Accelerator Pedal Position (ECM) J623 Electrical harness
GSensor 2185 Electrical harness T94 terminals or test box socket
connector
1 58
2 80
3 78
4 79
5 56
6 57

If the specification is not obtained:
- Check the wiring for an open circuit, short circuit to each other, Battery (+), or Ground (GND)
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
- Erase the DTC memory. Diagnostic Modes 01 - 09
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- 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.
- Assembly is performed in the reverse of the removal.

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

1. Check the DTC memory. Diagnostic Modes 01 - 09
2. If necessary, erase the DTC memory. Diagnostic Modes 01 - 09
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of Diagnosis