Electrically Adjustable Front Seat With Memory
+TElectrically Adjustable Front Seat With Memory:
WIRING DIAGRAM
Electrically Adjustable Front Seat With Memory: Component Location:
COMPONENT LOCATION VIEW
Electrically Adjustable Front Seat With Memory: Component ID:
COMPONENT ID
22A Fuse board behind the cover flap in the glove box.
54 Door switches in the door pillars.
230 Distribution terminal (+30 circuit) in main fuse box behind the glove box.
231 Distribution terminal (+54 circuit) in main fuse box behind the glove box.
348 Scan tool diagnostics data link connector under the right-hand
(H10-9) seat.
357 Switch, electrically adjustable driver's seat, on the outside of the seat.
357A-D Electric motors, driver's seat, under the seat.
357E-H Position sensor, electrically adjustable driver's seat, memory, under the seat on the corresponding motor shaft.
357J Switch, memory, on the outside of the driver's seat.
357K Electronic control module, electrically adjustable driver's seat with memory, under the seat.
2-Pin Connectors
H2-15 In the right-hand A pillar.
H2-33 In the left-hand A pillar.
3-Pin Connectors
H3-10 Under the left-hand seat, to the left on the electronics console.
H3-11 Under the right-hand seat, to the right on the electronics console.
8-Pin Connectors
H8-2 Under the right-hand seat.
H8-3 Under the left-hand seat.
Grounding Points
G14 Grounding point, left-hand front seat member
G24 Grounding point, right-hand front seat member.
DESCRIPTION OF OPERATION
The electrically adjustable front seat with memory is only fitted in the driver's position and consists of:
^ Two switches, one for manual seat adjustment and one for storing the settings and recalling them from the memory.
^ Electronic control module
^ Four electric motors with position sensors.
Switches
The switch unit consists of a number of switches, one pole of which is supplied with battery positive voltage from pin 8 on the electronic unit. When a switch is activated, battery positive voltage is routed to the corresponding switch input on the electronic unit.
Electronic Unit
Current (+30 circuit) is supplied via fuse 25 to the electronic unit which in its turn supplies this current to motors, potentiometers and switches.
The electronic unit continuously monitors the switches and if a valid combination of switches is activated, it carries out the corresponding operation.
When a motor is running, the electronic unit monitors current consumption and the position of the seat via the position sensors (potentiometers).
The electronic control unit's memory can store three different seat positions and five diagnostic trouble codes. The memory stores the information even if voltage is lost.
Motors
The motors are supplied with current via the electronic unit. The supply is battery positive voltage and its polarity changes with direction.
Position Sensors
The position sensors consist of potentiometers which are mounted on each motor shaft.
The potentiometers are supplied via the electronic unit with about 5 V on pins 1 and 3. When the motor shaft rotates, the voltage of the potentiometer's centre output, pin 2, varies between 0.4 V and 4.6 V. By measuring this voltage, the electronic unit can ascertain the position of the seat.
Manual Adjustment Of The Seat Setting
Only two motors can be run at the same time. If an attempt is made to operate more than two switches, all the motors will stop.
The forward/rearward movement of the seat and the angle of the seat cushion are limited by mechanical stops. The electronic unit therefore supplies current to these motors as long as each switch in the manual control is activated (up to a maximum of 1 minute).
The backrest has no mechanical stop to limit its forward and rearward inclination The limit is set by the electronic unit on the basis of signals from the backrest position sensor. For this reason, the electronic unit does not allow operation of the backrest motor if the position sensor is faulty.
Using The Memory
^ Adjust the seat to the desired position by means of manual adjustment switch 357.
^ Press the memory store button marked M in memory switch panel 357J and hold it depressed.
^ Press and release one of the memory buttons marked 1-3. The electronic unit now reads all positions and stores them in the memory. Release the button marked M.
If there is a fault in the position sensors, no new seat setting will be stored in the memory, but earlier settings are retained.
^ When using the memory unit to adjust the seat, press one of the memory buttons 1-3 and hold it depressed.
The electronic unit reads all position sensors and controls the motors until the seat setting corresponds to the setting stored in the memory, or until the memory button is released.
FAULT DIAGNOSIS HINTS
Faults detected by the electronic unit are stored in the memory as diagnostic trouble codes. These are read using the ISAT scan tool.
If the electronic control module detects a fault in any of the components or if a motor 5 moving too slowly, this component or motor is stopped.
The ISAT scan tool can also be used to read the position of each individual switch and the value of all position sensors.