1. Check for continuity between the No. 6 and No. 9 terminals of the tailgate closer unit 12P connector.

Is there continuity?

YES | - | Repair an open in the BLU/RED (HALF) wire between the No. 20 terminal of power tailgate control unit connector A (26P) and the No. 6 terminal of the tailgate closer unit 12P connector.■
NO | - | Faulty half latch switch, or an open circuit for HALF line in the tailgate closer unit; replace it.■

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