Symptom Chart - Four-Wheel Drive (4WD)

WARNING: This page is about a different variant/trim than selected.

Condition	Possible Sources	Action
No communication with the 4X4 control module	Scan tool Battery Junction Box (BJB) fuse Power supply circuit Smart Junction Box (SJB) fuse Ground circuit 4X4 control module Charging system	REFER to MODULE COMMUNICATIONS NETWORK article.
The vehicle does not shift between 4X4 AUTO and 4X4 modes correctly	Four-Wheel Drive (4WD) indicator(s) 4X4 control module BJB fuse SJB fuse Circuitry Transfer case clutch Mode Select Switch (MSS)	Go to Pinpoint Test D .
The Four-Wheel Drive (4WD) indicators do not operate correctly/do not operate	Instrument Cluster (IC) 4WD system fault High Speed Controller Area Network (HS-CAN) 4X4 control module Ignition switch and/or circuitry SJB fuse Circuitry	Go to Pinpoint Test J .
Four-Wheel Drive (4WD) does not engage at speed correctly	Transfer case clutch coil 4X4 control module Integrated Wheel End (IWE)	Go to Pinpoint Test E .
The front axle does not engage/disengage correctly	MSS IWE IWE solenoid Transfer case Vacuum leaks 4X4 control module Circuitry	Go to Pinpoint Test C .
Four-Wheel Drive (4WD) system jumps out of gear	Transfer case IWE vent MSS	Go to Pinpoint Test F .
Straight-line driveline wind-up	Unmatched tire sizes Unequal amounts of tire wear Unequal tire inflation pressures Unmatched front and rear axle ratios	Go to Pinpoint Test G .
The front axle makes noise in 2H mode only and generally under heavy throttle	Vacuum leaks Vacuum lines Vacuum check valves Vacuum reservoir IWE solenoid IWE	Go to Pinpoint Test H .
Grinding noise during 4WD system engagement, especially at high speeds	Front halfshaft speeds not turning at the same speed	INSTALL a new S-spring in the front differential. REFER to FRONT DRIVE AXLE/DIFFERENTIAL article for S-spring installation.
The transfer case makes noise	Tire inflation pressure Tire and wheel size	MAKE SURE that all tires and wheels are the same size and that the inflation pressures are correct.
	Tire tread wear	CHECK tire tread wear to see if there is more than 0.15 mm (0.06 in) difference in tread wear between front and rear. INTERCHANGE one front wheel and one rear wheel. ROAD TEST again.
	Internal components	OPERATE the vehicle in all transmission gears. If there is noise in the transmission in NEUTRAL, or in some gears and not in others, REMOVE and REPAIR the transmission. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - 6HP26 article. If there is noise in all gears, DISASSEMBLE the transfer case. REFER to TRANSFER CASE article. CHECK the planetary gears, the bearings, the upper and lower drive sprockets and drive chain for damage. INSTALL new parts as necessary.
	Fluid level	FILL with automatic transmission fluid. REFER to TRANSFER CASE article.
The vehicle binds in turns/resists turning/pulsates/shudders in a straight line	Unmatched tire sizes Unequal amounts of tire wear Unequal tire inflation pressures Unmatched front and rear axle ratios	Go to Pinpoint Test K .
The vehicle has no torque or inadequate torque at rear wheels in 4X4 AUTO mode	Transfer case Circuitry 4X4 control module	Go to Pinpoint Test I .
Unable to duplicate customer concern	4WD indicator 4X4 control module Transfer case and related components Wheel/tire assemblies	CARRY OUT the Four-Wheel Drive (4WD) System Functional Test. Go to Pinpoint Test I .