1. Disconnect the negative battery cable.
2. Remove the headlight cleaner switch. (See HEADLIGHT CLEANER SWITCH REMOVAL/INSTALLATION)
3. Inspect for continuity between the headlight cleaner switch terminals using an ohmmeter.


Headlight cleaner switch removal/installationMazda 6 Service Manual: Dtc b1318
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
...
Mazda 6 Service Manual: Filament inspection
1. Turn the ignition switch to ON position.
2. Turn the rear window defroster switch on.
Caution
Directly touching the rear window defroster filament with the lead
of the voltmeter will damage it. Wrap aluminum foil around the end of the
lead and test the filament by touching it with the ...