Power seat option is available for driver’s and passenger’s seat. Seats have a memory function and an integral diagnosis system. Memory function has 3 memory buttons for different seat settings. There is one control for seat cushion and one for backrest. Seat control module, which is located under seat, controls 4 motors. Three motors are under the seat and one is in the backrest. Memory-type control module takes seat position information from 4 position sensors.
Control module contains 9 relays: 2 for each motor and one main on/off relay. Motor No. 1 controls fore and aft movement of the seat. Motor No. 2 controls backrest angle, motor No. 3 controls seat cushion height at the rear, and motor No. 4 controls seat cushion height at the front.
If system detects a broken, shorted, or grounded wire, motors can then only be operated without their memory function. If system detects a broken, shorted, or grounded motor wire, that motor is disabled. Other motors can only be operated without their memory function.
If a control button is pressed for more than 30 seconds, a timer circuit cuts off power supply to motors by disabling main relay. Seat positions are held in an EEPROM which retains information indefinitely in case of power failure.
Download Volvo 850 Memory Power Seats.pdf
