Programming and Relearning
Throttle Valve Control Module, Adaptation
The adaptation process enables the engine control module to learn the different positions of the throttle valve with the ignition switched on and the engine not running. These positions are stored in the control module. The feedback signal indicating the position of the throttle valve comes from the two angle senders for throttle drive.
If the throttle valve control module -J338- or the engine control module is removed and refitted or replaced, or if the power supply to the engine control module is interrupted, the adaption process must be performed.
The learning process (adaption process) is carried out:
- Automatically - if the ignition is switched on for at least 10 seconds without operating the starter or depressing the accelerator, and if the engine control module registers a "learning requirement". (In this case, however, there is no way of knowing whether the adaption process was successful or not.) The engine control module will register a learning requirement if the previously stored voltage readings from the angle sensors do not correspond (within a certain tolerance range) to the new voltage readings.
- By selecting "Basic settings" (function 04), Display Group 060 with the ignition switched on.
NOTE: The engine will not start while the automatic adaption process is being performed.
Special tools and equipment
- VAS 5051 and VAS 5051/1
Requirements:
- No faults stored in Diagnostic Trouble Code (DTC) memory. Interrogating Diagnostic Trouble Code (DTC) memory.
- Engine not running; ignition switched on.
- Accelerator not depressed.
- Coolant temperature 10 to 95 degree C.
- Intake air temperature 10 to 90 degree C.
- Voltage supply to engine control module more than 12.7 V.
Work sequence
- Connect the vehicle diagnostic, testing and information system VAS 5051, and select the vehicle system "01 - Engine electronics" from the menu. When doing this the ignition should be switched on.
Display on VAS 5051:
- Select the diagnosis function "04 - Basic settings" from the menu -1-.
Display on VAS 5051:
1 - Enter display group
(figures up to 255)
- Using the keypad -2-, enter "060" to select Display group 060 and confirm entry with Q button.
When the Q key is pressed the current supply to the throttle valve positioner will be disconnected.
In this condition the throttle valve is pulled into an "emergency running" or default position by a spring in the throttle valve control module. The values supplied by the two angle senders for this position are stored in the engine control module.
The throttle valve is then opened by a predetermined amount. As soon as it reaches this position the current supply to the throttle valve positioner is again disconnected. The spring should then close the throttle valve mechanically to the previously learned default position within a specified period of time (spring test).
The throttle valve positioner then closes the throttle valve and the values supplied by the angle sensors in the throttle valve control module are stored in the engine control module.
If the engine control module disconnects the current supply to the throttle valve positioner while the vehicle is being driven, the result will be an increase in idling speed with fluctuating engine RPM (hunting) and very slow throttle response.
Display on VAS 5051:
- Check display values for throttle valve control module (display zones -3- and -4-).
Display Group 060:
NOTE: If the adaptation process is interrupted by the control module, the cause could be one of the following:
- The throttle valve is unable to close completely (e.g. because of dirt).
- Battery voltage too low.
- Throttle valve control module or wiring is defective.
- The engine was started or the accelerator depressed during the adaption process.
- Distortion of throttle valve housing (check bolts).
When the adaptation process is interrupted the message "Function is unknown or cannot be carried out at the moment" will appear on the fault reader display. The adaption process will start again automatically the next time the ignition is switched on (for several seconds).
- Press the <- button to exit from the function "04 -Basic settings"