1. Disconnect the negative battery cable.
2. Remove the driver-side air bag module. (See DRIVER-SIDE AIR BAG MODULE REMOVAL/INSTALLATION.)
3. Disconnect the audio control switch connector.
4. Measure the resistance and inspect for continuity between the cruise control switch terminals using an ohmmeter.


Audio control switch removal/installation
Audio amplifier removal/installationMazda 6 Service Manual: No. 1 one or more on-board diagnostic functions inoperative
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while doing the inspection to discover whether
poor contact points are the cause of any intermittent malfunctions. If there
is a problem, check to make sure connectors, terminals and wir ...
Mazda 6 Service Manual: Cargo compartment light switch inspection
1. Remove the liftgate lower trim. (See LIFTGATE LOWER TRIM
REMOVAL/INSTALLATION)
2. Disconnect the cargo compartment light switch connector.
3. Inspect for continuity between the cargo compartment light switch
terminals using an ohmmeter.
If not as specified, replace the liftgate lock.
...