Throttle Valve Control Module, Checking
Throttle Valve Control Module, Checking
Observe all safety precautions: => [ Safety Precautions ] Generic Scan Tool
View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions
Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.
For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.
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.
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) (J623) and the Throttle Position (TP) Sensor (G79)/Accelerator Pedal Position Sensor 2 (G185).
The Throttle Valve Control Module (J338) is made up of the following components:
• 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)
The Throttle Valve Control Module (J338) cannot be serviced separately and must be serviced as a unit.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check
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 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 1 to 3 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 appropriate service 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 Angle Sensor 1 (for Electronic Power Control (EPC)) (G187) at the Throttle Valve Control Module (J338) electrical harness connector terminals 1 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 test box.
If the manufacturers test box is not being used, perform the following step.
- Remove the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service information.
- Using a multimeter, check the Throttle Valve Control Module (J338) at electrical harness connector terminals to the Motronic Engine Control Module (ECM) (J623) electrical harness connector T60 terminals for an open circuit according to the wiring diagram.
Specified value: 1.5 ohms max.
If the specification is not obtained:
- Check the wiring for a short circuit to Battery (+), or an open circuit.
- If necessary, repair the faulty wiring connection.
- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
If no malfunction is detected in the wiring and if the voltage supply was not OK:
- Replace the Motronic Engine Control Module (ECM) (J623). Refer to appropriate service information.
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 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 ] Monitors, Trips, Drive Cycles and Readiness Codes.