Electronic Throttle Control Module: Testing and Inspection

Throttle Valve Control Module, Checking

• Use only gold-plated terminals when servicing terminals in harness connector of Throttle Valve Control Module (J338).

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Motronic Engine Control Module (ECM) (J220) 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.

• Throttle valve must not be damaged or dirty.

• Coolant Temperature at least 80° C.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing

Function

Throttle valve operation occurs by an electric motor (Throttle Drive (for Electronic Power Control (EPC)) (G186)) in the Throttle Valve Control Module (J338). It is operated by the Motronic Engine Control Module (ECM) (J220) and the Throttle Position (TP) Sensor (G69)/Throttle Drive Angle Sensor 2 (for Electronic Power Control (EPC)) (G188).

The Throttle Valve Control Module (J338) is made up of the following components:

• Throttle Drive (for Electronic Power Control (EPC)) (G186)

• Throttle Position (TP) Sensor (G69)

• Throttle Drive Angle Sensor 2 (for Electronic Power Control (EPC)) (G188)

The Throttle Valve Control Module (J338) cannot be serviced separately and must be serviced as a unit.

Start diagnosis

- Connect the scan tool.

- Switch ignition on.

- Using the scan tool, check the throttle valve position (absolute) at idle stop:





- Slowly depress the accelerator pedal to Wide Open Throttle (WOT) stop while observing the percentage display. The percentage display must increase uniformly.

- Using the scan tool, check the throttle valve position (absolute) at Wide Open Throttle (WOT) stop:





- End of diagnosis and switch ignition off.

If the specified values are not obtained:

- Remove the Throttle Valve Control Module (J338) far enough so that the electrical connector terminals are reached.

- Disconnect the Throttle Valve Control Module (J338) electrical harness connector - arrow -.





Checking resistance

- Using a multimeter, check the Throttle Drive (for Electronic Power Control (EPC)) (G186) at the Throttle Valve Control Module (J338) terminals 3 to 5 for resistance.





Specified value: 1.0 to 5.0 ohms (at 20° C)

If the specification was not obtained:

- Replace the Throttle Valve Control Module (J338).

If the specification was obtained:

Checking voltage supply and wiring

- Switch the ignition on.

- Using a Multimeter, check the Throttle Drive (for Electronic Power Control (EPC)) (G186) at the Throttle Valve Control Module (J338) electrical harness connector terminals 2 to 6 for voltage.

Specified value: at least 4.5 V

- Switch the ignition off.

If the specification was not obtained:

Checking wiring

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

- Install the Adapter Cable (121-pin) (VAG1598/31)

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

- Remove the Motronic Engine Control Module (ECM) (J220). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Using a Multimeter, check the Throttle Drive (for Electronic Power Control (EPC)) (G186) at Throttle Valve Control Module (J338) electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J220) electrical harness connector T121 terminals for resistance.









Specified value: 1.5 ohms max.

If the specification was not obtained:

- Check the wiring for an open circuit, 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 the voltage supply was OK:

- Replace the Throttle Valve Control Module (J338). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- 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 of diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:

- Replace the Motronic Engine Control Module (ECM) (J220). 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.