Symptom Chart - Four-Wheel Drive System

WARNING: This page is about a different car, the 2014 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

FOUR-WHEEL DRIVE SYSTEM SYMPTOM CHART

Condition	Possible Sources	Action
No communication with the TCCM	Scan tool DLC TCCM Wiring, terminals or connectors	REFER to MODULE COMMUNICATIONS NETWORK .
The 4X4 mode indicators do not operate correctly/do not operate	Instrument Panel Cluster (IPC) 4WD system fault HS-CAN TCCM	GO to PINPOINT TEST V .
The vehicle does not shift between 2H (2WD) and 4X4 modes correctly	Wiring, terminals or connectors MSS Transfer case TCCM	GO to PINPOINT TEST X .
The vehicle does not shift between 4A (4X4 AUTO) and 4H (4X4) modes correctly	MSS IWEs IWE solenoid Transfer case Vacuum leaks Front axle assembly TCCM Wiring, terminals or connectors	GO to PINPOINT TEST O .
Vehicle has no torque or inadequate torque at front wheels in 4A (4X4 AUTO) mode	Transfer case and related components IWEs and related components Wheel/tire assemblies	CARRY OUT the 4WD System Functional Test. GO to PINPOINT TEST U .
The vehicle does not shift between 4H (4X4) and 4L (4X4 LOW) modes correctly	Wiring, terminals or connectors Transfer case TR ABS wheel speed inputs IWEs TCCM Transmission drag torque	GO to PINPOINT TEST P .
4WD does not engage at speed correctly	Transfer case synchronization clutch Transfer case TCCM Front axle assembly Wiring, terminals or connectors	GO to PINPOINT TEST Q .
The front axle does not engage/disengage correctly	MSS IWEs IWE solenoid Transfer case Vacuum leaks Front axle assembly TCCM Wiring, terminals or connectors Fuses	GO to PINPOINT TEST N .
The 4WD system jumps out of gear	IWE vent line(s) MSS Transfer case	GO to PINPOINT TEST R .
Unable to duplicate customer concern	4WD system and/or related components	CARRY OUT the 4WD System Functional Test. GO to PINPOINT TEST U .
Unable to achieve flat tow (neutral tow) mode	Wiring, terminals or connectors HS-CAN IPC TCCM Door ajar switch Ignition switch	Go to PINPOINT TEST AH in Electronic Locking Differential (ELD) System, Diagnosis and Testing.