- No communication with the four wheel drive (4WD) control module (PCM)
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- Scan tool
- Data link connector (DLC)
- 4WD control module (PCM)
- Circuitry
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- The instrument cluster 4L and 4H indicators do not operate correctly/do not operate
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- Instrument cluster
- Circuitry
- 4WD control module (PCM)
- Ignition switch
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- The vehicle does not shift between two wheel drive (2WD) and 4WD modes correctly
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- Mode select switch (MSS)
- Transfer case
- Transfer case clutch
- Integrated wheel ends (IWEs)
- 4WD control module (PCM)
- Circuitry
- Ignition switch
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- The vehicle does not shift between 4H and 4L modes correctly
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- Transfer case
- MSS
- 4WD control module (PCM)
- Transmission drag torque
- Ignition switch
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- 4WD does not engage at speed correctly
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- Transfer case clutch coil
- 4WD control module (PCM)
- IWEs
- Ignition switch
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- The front axle does not engage/disengage correctly/makes noise in 2H under heavy throttle
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- MSS
- IWEs
- IWE solenoid
- Vacuum leaks
- 4WD control module (PCM)
- Front halfshaft
- Ignition switch
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- The 4WD system jumps out of gear
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- Transfer case
- IWE vent
- Mode select switch (MSS)
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- Straightline driveline wind-up
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- Tire inflation pressure
- Tire and wheel size
- Tire wear
- Axle ratio
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- Grinding noise during 4WD engagement, especially at high speeds
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- Front halfshaft speeds not turning at the same speed
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- Flashing 4H and 4L indicators 3 times every 2 minutes
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- Loss of CAN communication between 4WD control module (PCM) and instrument cluster
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- No communication with the 4WD control module (PCM)
- Ignition switch
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- The transfer case makes noise
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- Tire inflation pressure
- Tire and wheel size
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- MAKE SURE that all tires and wheels are the same size and that the inflation pressures are correct.
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- 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.
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- 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 - 4R70E/4R75E
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.
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- FILL with automatic transmission fluid. REFER to TRANSFER CASE
article.
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- Unable to duplicate customer concern
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- 4WD system and/or related components
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- CARRY OUT the Electronic Shift on the Fly (ESOF) Functional Test. Go to Pinpoint Test Q .
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