Remove the tailgate trim panel (see page 20-209). Open the tailgate. Disconnect the 4P connector from the tailgate lock actuator. Terminal side of male terminals Check for continuity between the terminals. There should be continuity between the No. 3 and No. 4 terminals when the tailgate lock knob switch is UNLOCK position. There should be no continuity between the No. 3 and No. 4 terminals when the tailgate lock knob switch is LOCK position.