Electronic Throttle Control Module: Testing and Inspection

Throttle Valve Control Module, Checking

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagram



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

Test requirements

• Fuses for Engine Control Module (ECM) (J623) 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.

Function

Throttle valve operation occurs by an electric motor (Throttle Drive (for Electronic Power Control (EPC)) (G186)) in the Throttle Valve Control Module ( J338) and is operated by the Engine Control Module (ECM) (J623) according to the signals supplied by the Throttle Position (TP) Sensor (G69)/Accelerator Pedal Position Sensor 2 ( G188 ).

Components of Throttle Valve Control Module (J338 ):

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

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

Function test

- Connect the scan tool.

- Switch ignition on.

- Select "Diagnostic mode 1: Check measured values".

- Select the measuring value "PID 17: Throttle valve position ".

- Check specified value of throttle valve position (absolute) at idle stop:





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

- Check specified value of throttle valve position (absolute) at Wide Open Throttle (WOT) stop:





- End diagnosis and switch ignition off.

If specified values are not obtained:

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

- Disconnect the electrical harness connector - 2 - from the Throttle Valve Control Module (J338).





Checking resistance

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





Specified resistance 4.0 ohms max.

If the specification is not obtained:

- Replace Throttle Valve Control Module ( J338).

If the specification is obtained:

Checking voltage supply and wiring

- Switch ignition on.

- Using the Multimeter, check the voltage of Throttle Drive (for Electronic Power Control (EPC)) (G186) at Throttle Valve Control Module (J338) between terminals 2+6.





Specified value: at least 4.5 V

- Switch ignition off.

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









Specified resistance 1.5 ohms max.

If the specification is not obtained:

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

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

- Check resistance values of Throttle Control Module J338 at T121 terminal or test box





- Value not received? Replace J338. If value received,

- 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.

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.