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: Brake/Clutch Fluid
Inspecting Brake/Clutch Fluid Level
WARNING
If the brake/clutch fluid level is low, have the brakes inspected:
A low brake/clutch fluid level is dangerous. A low level could indicate brake lining
wear or a brake system leak which could cause the brakes to fail and lead to an
accident.
The b ...
Mazda 6 Service Manual: Trunk Lid
WARNING
Never allow a person to ride in the trunk: Allowing a person to ride
in the trunk is dangerous. The person in the trunk could be seriously injured or
killed during sudden braking or a collision.
Do not drive with the trunk lid open: Exhaust gas in the cabin of a vehicle
is dangerous. ...