Memory Positioning Systems: Description and Operation

MEMORY SEAT SYSTEM
An electronic memory seat system is available on certain models. The memory system is able to store and recall all driver side power seat positions, and the drivers side view mirror positions. The system can be set for two different drivers. On vehicles with a factory installed radio connected to the Controller Area Network (CAN) data bus network, the memory system is also able to store and recall up to twenty radio station presets (ten AM and ten FM), also for two drivers. The memory system also will store and recall the last station listened to for each driver, even if it is not one of the twenty preset stations.

The memory system will automatically recall all of these settings when a button of the memory switch is depressed, or when the doors are unlocked using the Remote Keyless Entry (RKE) transmitter (if enabled). If the vehicle has more than two drivers the RKE transmitter recall of memory features can be disabled. This is a customer programmable feature of the overhead console.

The memory system also has a easy exit feature that will move the driver seat rearward 55 millimeters or to the end of its travel, whichever occurs first, when the key is removed from the ignition switch lock cylinder. This is a customer programmable feature of the overhead console.

The memory system includes the following components:
- Memory Selector Switch - located in the driver door trim panel.
- Driver Memory Mirror Module (DMMM) - located in the driver door, behind the trim panel.
- Passenger Memory Mirror Module (PMMM) - located in the passenger door, behind the trim panel.
- Hall Effect Sensors - Drivers Mirror - The hall effect sensor is permanently installed on the drivers side view mirror motor. This hall effect sensor is used to provide a reference signal to the memory heated seat mirror module, letting the module know the exact position of the mirror.
- Sentry Key Remote Entry Module (SKREEM) - located at ignition key cylinder.
- Remote Keyless Entry (RKE) Transmitter - located with ignition key.
- Memory Seat Module (MSM) - located underneath the driver seat and also controls the Adjustable Pedals.
- Hall Effect Sensors - Seat Track - These hall effect sensors are permanently installed in each of the power seat track motors. They are used to provide a reference signal to the memory heated seat mirror module, letting the module know the exact position of the seat cushion and recliner.
- Radio - located in the instrument panel center stack.
- Automatic Temperature Control (ATC) - located in the instrument panel center stack.

Certain functions and features of the memory system rely upon resources shared with other electronic modules in the vehicle over the Controller Area Network (CAN) bus. The CAN bus allows the sharing of sensor information. This helps to reduce wire harness complexity, internal controller hardware, and component sensor current loads. At the same time, this system provides increased reliability, enhanced diagnostics, and allows the addition of many new feature capabilities. For diagnosis of these electronic modules or of the CAN bus, the use of a scan tool and the proper diagnostic information are needed.

The Memory Seat Module (MSM) receives battery current through a 50 amp fuse in the Power Distribution Center (PDC) so that the power seats remain operational, regardless of the ignition switch position. When the driver memory seat switch control knob is actuated, a resistance signal is sent to the MSM via the Controller Area Network (CAN) bus circuit. The MSM is responsible for the 12 V battery feed and ground path to the power seat adjuster motor. The adjuster motor operates to move the power seat adjuster mechanism through its drive unit in the selected direction until the switch is released, or until the travel limit of the adjuster is reached.

The MSM receives memory set/position switch input through the CAN bus circuit. The MSM also receives hard wired input from the hall effect sensors, mounted on each of the driver power seat adjuster motors and the driver side view mirror motor. The programmed software in the module allows it to know where the seat/mirror is located in its designed travel by a pulse count generated from the hall effect sensors. This way, when the memory switch is depressed the module will power the seat adjuster/mirror motors until the correct preset location is achieved. The module will prevent the seat memory recall function from being initiated, if the transmission gear selector lever is not in the Park position, or if the vehicle is moving. These inputs are monitored over the Controller Area Network (CAN) bus circuit by the MSM.

A memory setting is saved by pressing the "set" button, then pressing either the memory "1" or "2" button within five seconds of pressing the "set" button.

A memory setting is recalled by pressing either the memory "1" or "2" button, or by pressing the unlock button on a "linked" Remote Keyless Entry (RKE) transmitter.

For driver safety, memorized settings can not be recalled if the transmission is in a position other than Park or the seat belt is latched.