1. Check for continuity between the No. 8 and No. 9 terminals of the tailgate closer unit 12P connector.

Is there continuity?

YES | - | Repair an open in the GRN/BLK (LACT) wire, between the No. 19 terminal of power tailgate control unit connector A (26P) and the No. 8 terminal of the tailgate closer unit 12P connector.■
NO | - | Faulty ratchet switch, or an open circuit for LACT line in the tailgate closer unit; replace it.■

1. Disconnect 12P connector from the tailgate closer unit.