Four-Wheel Drive (4WD) Control Module Symptom Chart

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

SYMPTOM CHART

Condition	Possible Sources	Action
The concern is unverifiable; no DTCs	The concern description is inaccurate.	GO to PINPOINT TEST A .
The transfer case makes noise	Tire inflation pressure. Tire and wheel size.	MAKE SURE all tires and wheels are the same size and brand, and the inflation pressures are correct.
	Fluid level.	FILL with the correct type and amount of lubricant. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
	Internal components.	OPERATE the vehicle in all transaxle gears. If there is noise in the transaxle in NEUTRAL, or in some gears and not in others, REMOVE and REPAIR the transaxle. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - CD4E for automatic transaxle, AUTOMATIC TRANSAXLE/TRANSMISSION - ELECTRONICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION (ECVT) for the electronically controlled continuously variable transmission (ECVT), or MANUAL TRANSAXLE/TRANSMISSION for manual transaxle. If there is noise in all gears, INSTALL a new transfer case. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
Leaking fluid from the transfer case vent	Transfer case.	DRAIN the fluid to the correct level. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
Leaking fluid from the transfer case vent	Vent tube.	REPAIR or INSTALL a new vent. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
Leaking automatic transmission fluid	Transfer case driven gear seal.	INSTALL a new transfer case driven gear seal. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
Leaking gear lubricant from the seals	The vent is plugged.	INSTALL a new vent. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
	Damaged seals.	For automatic transaxle, INSTALL new seals. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
	Damaged seals.	For manual transaxle, INSTALL a new transfer case. REFER to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .
No communication with the 4-wheel drive (4WD) control module	Smart junction box (SJB) fuse(s): 18 (10A). 35 (5A). 4WD control module. Circuitry.	GO to PINPOINT TEST B .
Four-wheel drive (4WD) control module battery voltage is high or low	Concern with voltage regulator or generator. Smart junction box (SJB) fuse 18 (10A). Intermittent open power circuit. Relay failure inside 4WD control module.	GO to PINPOINT TEST C .
Four-wheel drive (4WD) control module received no/invalid data from powertrain control module (PCM)	Invalid data received from PCM. Data out of range.	GO to PINPOINT TEST D .
Four-wheel drive (4WD) control module received no/invalid data from anti-lock brake system (ABS) module	Invalid data received from the ABS module. Data out of range.	GO to PINPOINT TEST E .
Controller area network (CAN) communications bus fault	CAN bus fault. Powertrain control module (PCM) fault. Anti-lock brake system (ABS) fault. Four-wheel drive (4WD) control module.	GO to PINPOINT TEST F .
Vehicle has no or inadequate torque at rear wheels	Rear axle.	REFER to REAR DRIVE AXLE/DIFFERENTIAL .
Vehicle has no or inadequate torque at rear wheels	Tire/wheels. Active torque coupling. Smart junction box (SJB) fuse(s): 18 (10A). 35 (5A). Four-wheel drive (4WD) control module. Circuitry.	GO to PINPOINT TEST G .
The 4-wheel drive (4WD) indicator does not operate correctly	Instrument cluster. Four-wheel drive (4WD) control module. Circuitry.	GO to PINPOINT TEST H .
Vehicle binds in a turn or resists turning	Four-wheel drive (4WD) control module. Active torque coupling. Circuitry.	GO to PINPOINT TEST I .
Tire/axle out of acceptable range	Wheels/tires. Wheel speed sensors. Anti-lock brake system (ABS) module. Four-wheel drive (4WD) control module.	GO to PINPOINT TEST J .
Vehicle pulsates or shudders in a straight line	Four-wheel drive (4WD) control module. Active torque coupling. Circuitry.	GO to PINPOINT TEST I .