Main Relay

Ensure main relay clicks when ignition is turned on and off.
If no sound is heard, unplug relay. Apply 12 volts to terminal "A" and ground terminal "B". See Fig 1 .
Use ohmmeter to check terminal continuity. Terminals "C" and "D" should have continuity with 12 volts applied. There should be no continuity with no voltage applied. If relay does not respond as described, replace main relay.

Fig 1: Testing Main Relay

Courtesy of MAZDA MOTORS CORP.