Prior to replacing the 4WD ECU, check the 4WD ECU's clutch learing with the GDS tool.
(Refer to 4WD Control System - "Repair procedures")
Disconnect the battery negative cable from the battery
Disconnect the 4WD ECU connector (A).
Loosen the nuts (A) and then remove the 4WD ECU.
Tightening torque:
9.8 ~11.8N.m (1.0~1.2kgf.m, 7.2~8.7lb-ft)