Brake Pad Wear Sensor: Testing and Inspection

Brake Light Warning:

The solid state module, located in the instrument cluster, closes the Brake Pad Wear Indicator circuit to ground when an open condition in the brake pad sensor circuit exists.

Note! Voltage at brake wear sensor connector is within 1 volt of battery voltage.

Condition: Brake Pad Wear indicator stays ON after start-up bulb check sequence or intermittently illuminates during brake application.

1 Turn ignition switch on.

2 Check for voltage at LH front brake pad sensor connector:
No volts: check for voltage at I/P connector X16, pin 25. If OK check for an open circuit between I/P connector X16, pin 25, and front brake sensor connector X118, pin 2.

3 Check LH front brake pad sensor for continuity and wear:
No continuity: replace sensor.
Wear: If pad sensor is worn to the point that the wire running through the sensor is exposed, replace sensor.

4 Check for voltage at RH rear brake pad sensor connector:
No volts: check for an open circuit between the RH rear sensor connector X713, pin 1 and the LH front sensor connector X118, pin 1.

5 Check RH rear brake pad sensor for continuity and wear:
No continuity: replace sensor.
Wear: If pad sensor is worn to the point that the wire running through the sensor is exposed, replace sensor.

6 Check voltage at I/P connector X16 pin 10:
No volts: check for open circuit between I/P connector X16, pin 10, and the RH rear brake pad sensor connector X713, pin 2.

7 If brake pad sensor circuit is OK yet the Brake Pad Wear Indicator is still ON, the fault exists in the I/P Cluster. Perform tests on the I/P using BMW diagnostic equipment. Testing and Inspection