4WD Will Not Engage

Test power to transfer case switch. With ignition on, connect test light to ground and backprobe Brown wire terminal at transfer case switch connector. Test light should light. If so, proceed to next step. If not, inspect 25-amp 4WD fuse in fuse block. If fuse is okay, attach test light to ground and backprobe Pink/White terminal at convenience center. Test light should light. If so, repair open in Brown wire between convenience center and transfer case switch. If not, repair open in Pink/White wire between convenience center and 4WD fuse in fuse block.
Test transfer case switch. With transfer case shift selector in 4WD position and ignition on, attach test light to ground and backprobe Light Blue wire terminal at transfer case switch. Test light should light. If so, proceed to next step. If not, replace transfer case switch.
NOTE: Remainder of transfer case electronic testing and diagnosis is performed with transfer case gear selector in 4WD position and ignition on.
Test front axle solenoid power circuit. Attach test light to ground and backprobe Light Blue wire terminal of disconnected front axle solenoid. Test light should light. If so, proceed to next step. If not, repair open in Light Blue wire between front axle solenoid and transfer case switch.
Test front axle solenoid. Attach test light between Light Blue wire terminal and Black wire terminal of connected front axle solenoid. If test light lights, replace front axle solenoid and proceed to next step. If test light does not light, repair open in Black wire between front axle solenoid and ground. If no opens in circuit are found, replace transfer case relay.