1. Connect the connector to the running light unit.
2. Connect the negative battery cable.
3. Measure the voltage at the running light unit using voltmeter.
4. If the value are not as specified in the Terminal Voltage List (Reference), inspect the parts under Action and related wiring harnesses.
5. If the system does not work properly even though the parts or related wiring harnesses do not have any malfunction, replace the running light unit.
Terminal Voltage List (Reference)



Running light unit removal/installationMazda 6 Service Manual: Blind Spot Monitoring (BSM) (Some models)
The Blind Spot Monitoring (BSM) is designed to assist the driver in checking
the area to the rear of the vehicle on both sides during lane changes by notifying
the driver of the presence of vehicles approaching from the rear in an adjacent
lane.
The Blind Spot Monitoring (BSM) detects vehicle ...
Mazda 6 Service Manual: Door switch removal/installation
Front
1. Disconnect the negative battery cable.
2. Remove in the order indicated in the table.
3. Install in the reverse order of removal.
Rear
1. Disconnect the negative battery cable.
2. Remove in the order indicated in the table.
3. Install in the reverse order of removal. ...