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: Personalization Features
The following personalization features can be set or changed by the customer
or an Authorized Mazda Dealer. Consult an Authorized Mazda Dealer for details.
Additionally, some of the personalization features can be changed by the customer
depending on the feature.
Personalization features and s ...
Mazda 6 Service Manual: Dtc c1148, c1158, c1168, c1178, c1233, c1234, c1235, c1236
Caution
When attaching the tester lead to the ABS (ABS/TCS) HU/CM harness
connector, the SST (49 G066 001) must be used. (See ABS (ABS/TCS) HU/CM
INSPECTION.)
Diagnostic procedure
...