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Brief description, PSM

Brief description, PSM

The system includes:


• Electrically adjustable driver's seat with PSM

• Switch unit

• Motors

• Hall sensors

• Memory buttons


Electrically adjustable driver's seat with PSM

An electrically adjustable driver's seat is available for the Saab 9-3 as an option. An integral PSM system (Power Seat Memory) is included in the system. The PSM provides the driver's seat with a memory function, which makes it possible to store 3 different seat settings that can then be called up automatically when the relevant memory button is depressed.

The settings in memory of the seat position are sent on the bus and SID indicates with an acoustic signal. The PSM system also sends information to the DICE/diagnostic tool.

PSM receives information from TWICE on the status of the driver and passenger seats. This information affects the operation of the seats.

Switch unit

The switch unit is located on the outer side of the driver's seat. When a valid selection of switch or memory buttons is detected, the control module performs the corresponding function, i.e. it controls the motors as for manual operation without the memory function.

Motors

The motors are controlled by the switches in the switch unit and are monitored by the PSM. When the motors are running, the control module detects the pulses from the Hall sensors, which are used for programming. To change the direction of rotation of the motors, the polarity of the motor is reversed.

Hall sensors

The pulse emitters for the seat are of the Hall sensor type and integral to the motors for the function concerned.

On the motor shaft is a 2-pole magnetic ring (north/south). In the end of the motor is a Hall sensor which detects changes in the magnetic field. When the motor is running, the magnetic changes occur twice per rotation.

Memory buttons

The switch for the memory and memory store function comprises four buttons; three memory buttons, ”1”, ”2” and ”3”, and a memory store button ”M”.

When settings are being stored in memory, the control module reads all Hall sensors and stores their values in an internal seat memory. The seat memory is non-volatile and retains the data even when the control module power is turned off.