Throttle Valve Control Module, Checking

Diagnostic Procedures

Throttle Valve Control Module, Checking

Special tools, testers and auxiliary items required

• multimeter.

• Wiring diagram.

Test requirements

• 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.

• Throttle valve must not be damaged or dirty.

• Coolant Temperature at least 80° C.

Test procedure

- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions

- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions

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

Start diagnosis

Function

Throttle valve operation occurs by an electric motor (Throttle Drive (for Electronic Power Control (EPC)) (G186)) in Throttle Valve Control Module (J338). It is operated by Motronic Engine Control Module (ECM) (J623) according to specifications of Throttle Position (TP) Sensor (G79)/Kickdown Switch/Closed Throttle Switch (G185).

Components of Throttle Valve Control Module (J338):

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

• Throttle Drive Angle Sensor 1 (for Electronic Power Control (EPC)) (G187)

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

Function test

- 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:





- 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). Refer to the Repair Information.

If the specification was obtained:

- Check the voltage supply of the Throttle Valve Control Module (J338) to the Motronic Engine Control Module (ECM) (J623).

- .

Checking voltage supply and wiring

- Switch the ignition on.

- Using a multimeter, check the Throttle Drive (for Electronic Power Control (EPC)) (G187) 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:

- 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) (J623) electrical harness connector T60 terminals for an open circuit.









Specified value: 1.5 ohms max.

If the specification is not obtained:

- Check the wiring for high resistance, an open or a short to voltage or ground.

- If necessary, repair the faulty wiring connection.

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

If the DTC does return, no malfunction is detected in the wiring and the voltage supply is OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the Repair Information.

- 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. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

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