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lead object cutting in close to the front of the vehicle, ACC may not sense the lead object in time for intervention, driver intervention is required. Activation Conditions The following preconditions must be met for ACC to become operational: " Engine speed > 512 RPM " No failure of Irreversible faults present in ACC " ACC system ON " Driving Speed > 20 MPH " Park, Reverse or Neutral not engaged " Parking brake not engaged " DSC not active 13 ACC Operating Modes Initialization Mode All the ACC system components are checked after KL15 is active. The Radar sensor is checked from 20 km/h. Passive Mode Activation conditions are satisfied, ACC can be switched on by the Stalk Switch. Standby Mode ACC can be activated by the driver moving the stalk switch towards the instrument cluster + or towards the steering wheel - . Active Control Normal ACC control mode in which the vehicle is controlled with Mode automatic acceleration or deceleration. Suspend Mode ACC is not active, speed is controlled by the driver. To-Standby Mode Allows a smooth transition to Standby Mode when ACC is deactivat- ed by the driver. Brake only Mode Only brake activation is possible, no DME intervention. This mode is active under the following conditions: -Fault in the DME -Radar Sensor Blindness -DSC intervention active -Parking Brake Activated Mode is terminated by accelerator pedal movement, or ACC deactivation. Failure Mode If a malfunction is detected ACC automatically switches directly into failure mode and the system is non-functional. Deactivation The ACC is deactivated in several ways: " Raising or lowering of the Stalk Switch " Pressing the brake pedal " Placing the transmission in Neutral " Deactivating the DSC System " Failure of one of the subsystems (Automatic Deactivation) " Sensor Blindness (Automatic Deactivation) " Vehicle speed drops below the minimum operating range (Automatic Deactivation) " The DSC is active beyond a preset time threshold (Automatic Deactivation) Lens Heater The lens of the ACC sensor is heated to ensure better operation in winter and adverse con- ditions. The heating coil is integrated into the plastic lens body. 14 ACC Lens heating is temperature dependent as measured by an internal temperature sensor in the ACC unit. Despite the heater it is not possible to prevent sensor Blindness in all conditions. Faults with the lens heating system are registered in the ACC unit fault memory. Fault Memory Each module in the ACC system network stores its own faults. Faults that affect ACC oper- ation are passed on the ACC control unit for action, ie. deactivation of ACC. The ACC control unit stores and acts upon two different types of faults: " Irreversible Fault ACC itself has detected an irreversible fault or communication is no longer possible with the DME or DSC (via the PT CAN). ACC is inactive until the fault is repaired and cleared. " Reversible Fault ACC has detected a reversible fault in itself or a partner control unit. If the fault goes away ACC is immediately available for activation. An entry is made in the fault memory. Alignment It is essential that the sensor be correctly aligned for proper system operation. Horizontal mis-alignment will result in erroneous reaction to objects in a neighboring lane or a delayed reaction to objects in the same lane. ACC can compensate for minor horizontal misalignments up to 1 , with slight function impairments. In the event of more serious deviations, ACC will shut down and not be avail- able for operation. The alignment procedure is only possible with the DISplus or the GT1 and the special tools for ACC adjustment (PN 81-10-0-021-292). Note: The tool is used in conjunction with other BMW special tools. Refer to SIB B03 01 01. Always refer to the latest bulletins and repair instructions. 15 ACC Review Questions 1. What does the radar sensor monitor? 2. What is the meaning of the following symbols when displayed in the Instrument Cluster? 3. The following distance time intervals are? 4. How does ACC determine if brake application is necessary for proper deacceleration? 5. List the situations in which the ACC may reach its limitations. 16 ACC [ Pobierz całość w formacie PDF ] |