Programming and Relearning
Throttle Valve Control Module -J338-, Adapting
The adaptation process enables the Engine Control Module (ECM) to learn the various 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 throttle drive angle sensors.
If the Throttle Valve Control Module -J338- or the Engine Control Module (ECM) are removed, installed or replaced or if the voltage supply from the Engine Control Module (ECM) is interrupted, adaptation must always be performed.
The learning process (adaptation process) is performed:
- Automatically if the ignition is switched on once for at least 10 seconds without activating the starter or the accelerator pedal and the Engine Control Module (ECM) recognizes "adaptation requirement". In this case, however, it is not obvious whether the adaptation process was successful or not. Adaptation requirement is recognized if stored voltage values from the angle sensors do not coincide with current measured voltage values in a certain tolerance band.
- By initiating the basic setting (Function 04) of display group 060 with ignition switched on.
NOTE: Engine will not start during automatic adaptation.
Special tools and workshop equipment required
- VAS 5051.
- VAS 5051/1 adapter.
Preconditions:
- No DTCs recorded in DTC memory; check DTC memory.
- Engine stopped, ignition switched on.
- Accelerator pedal not depressed.
- Coolant temperature 10...95 degree C
- Intake air temperature 10...90 degree C
- Voltage supply to Engine Control Module (ECM) greater than 12.7 V.
Procedure:
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 - Engine electronics" in selection. Ignition must be switched on.
Display on VAS 5051:
- Under -1- select diagnostic function "04 - Basic setting".
Display on VAS 5051:
1 - Enter display group.
- Enter "060" for "display group number 060" in field -2- and confirm entry by pressing -Q- button.
Display on VAS 5051:
- Activate basic setting by pressing -A- button.
- Check specifications for Throttle Valve Control Module -J338- in display fields -3- and -4-.
The throttle valve drive is initially connected without voltage present.
In this condition, the throttle valve is pulled into an emergency running position by a mechanical spring which is located in the Throttle Valve Control Module -J338-. The values supplied by the two angle sensors in this emergency running position are stored in the Engine Control Module (ECM).
The throttle valve is then opened by a predetermined amount. When this value is reached, the throttle valve drive is again disconnected from the voltage supply. The mechanical spring should then close the throttle valve to the previously learned emergency running position within a specified period of time (spring test).
The throttle valve drive then closes the throttle valve; the values supplied by the angle sensors in the Throttle Valve Control Module -J338- are stored in the Engine Control Module (ECM).
If the Engine Control Module (ECM) disconnects the throttle valve drive from the voltage supply while the vehicle is being driven, the result will be an increased and fluctuating idling speed and a very poor throttle response.
Display Group 060:
**NOTE:
- The control module can abort adaptation for the following reasons:
- The throttle valve cannot close completely (e.g. contamination).
- The battery voltage is too low.
- Throttle Valve Control Module -J338- or wire connection is faulty.
- Engine is started during adaptation or accelerator pedal is operated.
- Tension of throttle valve housing (check bolts).
When adaptation process is interrupted, message "Function is unknown or cannot be carried out at the moment" is displayed on tester. The next time the ignition is switched on (for several seconds), the adaptation process is automatically performed again.
- Exit function "04 - Basic setting" by pressing <- button.