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: Antilock Brake System (ABS)
The ABS control unit continuously monitors the speed of each wheel. If one wheel
is about to lock up, the ABS responds by automatically releasing and reapplying
that wheel's brake.
The driver will feel a slight vibration in the brake pedal and may hear a chattering
noise from the brake system ...
Mazda 6 Service Manual: Cell Phones
WARNING
Please comply with the legal regulations concerning the use of communication
equipment in vehicles in your country: Use of any electrical devices such
as cell phones, computers, portable radios, vehicle navigation or other devices
by the driver while the vehicle is moving is dangerous ...