1. Check for continuity between the No. 7 and No. 9 terminals of the tailgate closer unit 12P connector.

Is there continuity?

YES | - | Repair an open in the BLU/BLK (LATCH) wire between the No. 18 terminal of power tailgate control unit connector A (26P) and the No. 7 terminal of the tailgate closer unit 12P connector.■
NO | - | Faulty full latch switch, or an open circuit for LATCH line in the tailgate closer unit; replace it.■

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