4WD Control Symptom Diagnosis

Diagnose 4WD system after performing the following inspections.

4WD CONTROL SYMPTOM DIAGNOSIS REFERENCE CHART

Condition	Possible Cause	Action
4WD system does not operate	2WD/4WD switch faulty	Check switch referring to 2WD/4WD SWITCH INSPECTION .
	Coupling air temperature sensor faulty	Check coupling air temperature sensor referring to COUPLING AIR TEMPERATURE SENSOR INSPECTION .
	Coupling assembly faulty	Check coupling assembly referring to COUPLING ASSEMBLY INSPECTION .
	Wiring or grounding faulty	Repair as necessary .
	4WD control module faulty	Check 4WD control module referring to INSPECTION OF 4WD CONTROL MODULE AND ITS CIRCUITS .
	MAF sensor faulty	Check MAF sensor and its circuit .
	Accelerator pedal position (APP) sensor faulty	Check accelerator pedal position (APP) sensor and its circuit .
	CKP sensor faulty Check	CKP sensor and its circuit .
	Front and/or rear wheel speed sensor faulty	Check front and/or rear wheel speed sensor and its circuit .
	Steering angle sensor faulty	Check steering angle sensor and its circuit .
	ABS/ESP® control module faulty	Check ABS/ESP® control module and its circuit .
	ECM faulty	Check ECM and its circuit .
Noise	Damaged or worn bearing(s)	Refer to REAR DIFFERENTIAL INSPECTION .