Maneuvering seats without memory
Power seats without memory do not have memory management buttons. The seat motors can only be operated directly via the control panel. This type of seat does not have a power seat module (PSM). The seat motors are directly connected to the control panel. For further information, see the relevant Wiring Diagram information.
The primary task of the power seat module (PSM) is to manage the functions for
- seat operation
- storage of memory positions (seat positions only).
The control module is under the seat on the driver's side. The seat must be removed in order to replace the control module.
The power seat module (PSM) communicates with directly connected components and with other control modules via CAN communication.
The control module checks activations and input and output signals via an integrated diagnostic system. A diagnostic trouble code (DTC) is stored in certain cases if the control module detects a fault.
Any diagnostic trouble codes (DTCs) are stored in the control module memory. The data can be read off using VIDA.
A simple way to check that the power seat module is supplied with power and grounded is to move the seat.
If the voltage is below 8.5 V or above 16.0 V, the power seat module (PSM) will not function. If the voltage increases to above 9.0 V or falls below 15.5 V, the control module will function again.
For further information, also see the relevant Signal specifications.
The chart below summarizes input and output signals to and from the power seat module (PSM) (4/52). The signal types are divided into directly connected signals, serial communication and controller area network (CAN) communication. The illustration below displays the same information with the Volvo component designations.
| Input signals | Output signals |
|---|---|
| Directly connected | Directly connected |
| Control panel (3/26) with: Control buttons (eight input signals, two buttons) Memory button 1, 2 and 3 Programming button (MEM). Hall sensors (four integrated into the seat motor) Control circuit connected to the control panel. | Seat motors (6/16-19) (four units). |
| Via Controller Area Network (CAN) communication | Via Controller Area Network (CAN) communication |
| Central electronic module (CEM) (4/56) Upper electronic module (UEM) (4/70). | Driver door module (DDM) (3/126) Passenger door module (PDM) (3/127). |
