Memory Control Module
Memory Control Module
NOTE: Memory Control Module Location (LHD shown, RHD similar)
The memory control module, located under the driver's seat, relies upon a number of inputs to control various outputs. As with all electronic control modules, the unit needs information regarding the current operating conditions of the engine and other related systems before it can make calculations, which determine the appropriate outputs.
All memory values are stored in the non-volatile memory, EEPROM. The current motor positions, which are monitored by the control modules integral Hall sensors, are stored in the EEPROM. If a loss of power occurs, upon power reconnection the current motor position are recalled from the memory and adopted as the current positions. This will allow the relative memory positions to be retained without any need to re-calibrate. The memory control module checks the integrity of all data stored in the EEPROM each time it exit's stand-by mode. In the event that the data is corrupt, the control module adopts the default values for all of the programming options. All memory positions are deemed as invalid and the software will perform as if there are no memory positions stored. Following the procedure for storing a memory position again will reset the relevant memory and allow full functionality.
Stall Detection
Seat, steering column and mirror motors are deemed to have stalled if there is no change in the inputs that are received from the corresponding feedback sensors for 200 ms (seat), 1000 ms (mirror & steering column) while that axis is being driven.
If a stall condition is detected then the drive to that axis is cancelled for the remainder of that memory operation (memory recall) or until the switch is re-selected (manual movement).
If the motor movement has stopped due to loss of sensor feedback, either stall or sensor failure, then that axis may be activated again, to move past the stall position, by re-selecting the appropriate switch. This allows control of the motor to be maintained if sensor feedback is lost.
Upon re-selection of movement, if sensor pulses are detected then the motor will continue to be driven until the switch is released or another stall condition is detected. If sensor feedback is not detected then the motor is only driven for 0.5 second and then stops until the switch is released and then pressed again, when a further 0.5 second of activation is permitted, and so on.
For all seat motor and steering column manual movements, whenever a motor is driven and a stall occurs, the memory control module records the position at which the stall occurred. If movement occurs beyond a stall position, then that position is erased from the control modules memory. This will always allow movement past a previously recorded stall position once movement has been registered beyond that position. This is the case for both manual and memory movement.
Initialization
When a replacement memory control module is fitted to a seat it should be initialized so that the control module can learn the seats and steering column maximum and minimum adjustment values. This is achieved by:
^ adjusting all seat movement axis from one end of travel to the other; slide, recline, height and tilt
^ adjusting all steering column movement from one end of travel to the other; rake and reach.
Battery Monitor
If the battery voltage drops below 10.5 Volts, then the memory control module ignores all requests for a memory recall, including lazy entry, or easy entry/exit until the battery voltage has reached 11.5 Volts. This will conserve as much power in the vehicle battery as possible to enable engine cranking.
Stand-by Mode
The memory control module supports a stand-by mode to keep power consumption to a minimum.
The control module will enter stand-by mode upon receipt of a LIN bus 'SLEEP' message from the Central Junction Box (CJB). Alternatively, a time period of 3 seconds after the LIN bus network has remained quiet provided there are no motors being driven at that time and there are no valid switch requests.
If there is a failure with the LIN bus network then the seat will be operational in 'inch mode' only.
If the control module is being prevented from entering stand-by mode due to motor movement, memory recall or switch operation, then it will enter stand-by mode when the current function has terminated.
NOTE: In the case of a memory recall, all memory recall operations should be carried out before entering stand-by mode, not just the current motor movement.
The control module will exit stand-by mode if there is any LIN bus activity. When the control module exits stand-by mode it must verify the 'System Enable Status' in order to recognize when it should respond to a switch request.