Fault code 0538: Diagnosis/troubleshooting

WARNING: Danger of injury from limbs being trapped or severed.

NOTE: To gain access to the driver's memory seat adjustment control unit, tilt the driver's seat back.

NOTE: Visual inspection: In the next troubleshooting section, first check that the affected pins on the driver's memory seat adjustment control unit plug connection are not damaged or corroded. The wiring and plugs of the affected components must also be checked for external damage and correct contact. Repair damaged or corroded pins if possible, otherwise replace affected pins. Repair or replace damaged wires.

NOTE: Sporadic faults: In the event of sporadic faults, wiring points attached to moving parts on and in the vehicle must be checked systematically. Various statuses that can cause faults must be simulated with the help of the wiring diagram.

NOTE: Battery voltage: A battery voltage of between 11.4 and 14.5 V is required for the following troubleshooting procedure. This must be checked and provided, if necessary. On the vehicle electrical system, the voltage to the fuse (input side) must be guaranteed.

NOTE:

The power supply for the Hall-effect sensors in the positioning motors are combined into two groups of three and one group of two Hall sensors respectively.
Hall sensor group 1 on connector socket E, pin 6 (Hall sensor 1): the sensors for seat fore-and-aft, angle and height adjustment respectively
Hall sensor group 2 on connector socket F, pin 6 (Hall sensor 2): the sensors for backrest angle, vertical lumbar height and horizontal lumbar height adjustment respectively
Hall sensor group 3 on connector socket P, pin 6 (Hall sensor 5): the sensors for horizontal and axial steering column adjustment respectively

DIAGNOSIS/TROUBLESHOOTING PROCEDURE

Work instruction			Display OK	If not OK
1	Visual inspection	Switch off ignition Check plug connection of connectors E, F and P on driver's memory seat adjustment control unit for damage (corroded or bent pins)	Go to Step 2	Repair plug → End
2	Check reference voltage for Hall sensor 1 at memory seat adjustment control unit	Pull plug E off the driver's memory seat adjustment control unit Switch on ignition Measure voltage between pin 6 of the driver's memory seat adjustment control unit and ground. To do this, actuate the motors of Hall sensor group 1 in turn	approx. 12 V Go to Step 3	Go to Step 5
3	Check reference voltage for Hall sensor 2 at memory seat adjustment control unit	Switch off ignition Pull plug F off the memory seat adjustment control unit Switch on ignition Measure voltage between pin 6 of the driver's memory seat adjustment control unit and ground. To do this, actuate the motors of Hall sensor group 2 in turn	Approx. 12 V Go to Step 4	Go to Step 5
4	Check reference voltage for Hall sensor 5 at memory seat adjustment control unit	Switch off ignition Pull plug P off the memory seat adjustment control unit Switch on ignition Measure voltage between pin 6 of the driver's memory seat adjustment control unit and ground. To do this, actuate the motors of Hall sensor group 5 in turn	Approx. 12 V → End	Go to Step 5
5	Replace driver's memory seat adjustment control unit		→ End