Mazda 3 Service Manual: Starter Interlock Switch Removal/Installation [C66 M R]
1. Remove the battery cover..
2. Disconnect the negative battery cable..
3. Disconnect the starter interlock switch connector.
4. Remove the starter interlock switch from the pedal bracket.
5. Insert a new starter interlock switch into the pedal bracket hole in the direction indicated by arrow A.
6. Slide the starter interlock switch pressing it in the direction indicated by arrow B until it is locked.
7. Fully depress the clutch pedal in the direction of arrow C, and verify that a click sound from the starter interlock switch is heard.
8. Install in the reverse order of removal.
9. Fully depress the clutch pedal, and verify that the engine starts.