It is usually the pad in contact with the piston that wears faster with a faulty caliper.You would think both inner and outer pads would wear the same but it is always the pad in contact with the piston that wears uneven with a sticking caliper.
Below is the calibration procedure for the electronic park brake.
Electronic Park Brake (EPB) - Re-Calibration Procedure
On some 2003 MY-on S-TYPE vehicles, a customer may report a concern of premature parking brake pad wear or the brakes binding. This condition can result if the electronic park brake (EPB) system is not re-calibrated after the removal of the rear brake calipers to replace the brake pads.
Should a customer express concern regarding the above, refer to the calibration procedure detailed in this bulletin.
1. Reset the EPB module:
a. Switch off the ignition.
b. Disconnect the battery for 30 seconds. For additional information, refer to S-TYPE Workshop Manual Section 414-01.
c. Reconnect the battery.
2. Start the engine.
3. Firmly apply and release the footbrake five times.
4. Confirm that the message "NOT CALIBRATED" or "APPLY FOOT AND PARK BRAKE" is displayed on the instrument cluster message center. This indicates that the parking brake is in calibration mode.
5. Lightly press the footbrake pedal.
6. Apply the parking brake by using the EPB switch.
7. Release the parking brake.
8. Release the footbrake.
9. Confirm that the brake warning lamp is no longer illuminated on the instrument pack and that the "NOT CALIBRATED" message is no longer displayed in the message center.
10. Apply and release the EPB five times to ensure no error is present.
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