Home ReviewsRefund
Home/Ford/Explorer/Ford Explorer IV (2005-2010)/Repair manual/Transfer Case/Four Wheel Drive (4WD) Systems: Overview
Contents Wiring diagrams Section: Transfer Case All sections

Four Wheel Drive (4WD) Systems: Overview Ford Explorer IV

Transfer Case 29 illustrations ~11856 words

Principles of Operation

The automatic, all wheel drive (AWD) transfer case has no external controls. A 2-piece aluminum case houses the assembly. The unit is chain-driven. A differential provides torque to the front and rear transfer case outputs. The differential transmits torque at the ratio of 40% to the front output and 60% to the rear output.

Torque flows through the input shaft to the front planetary gear assembly outward to the ring gear to the upper output shaft. Torque also flows through the front planetary gear assembly to the overdrive sun gear outward to the upper drive sprocket. The torque flow continues from the upper drive sprocket through the drive chain to the lower drive sprocket to the front output shaft. The differential provides the connection between the ring gear and the overdrive sun gear.

The one-speed torque-on-demand (TOD) transfer case modes are controlled through the 4X4 control module.

The modes are

  1. All wheel drive (AWD) AUTO - torque is supplied to the front and rear driveshaft as needed to maintain traction. AWD mode can be changed to AWD LOCKED mode by pressing the message center SETUP button; the message AWD AUTO will be displayed, press RESET within 4 seconds, then the message AWD LOCKED will be displayed and the 4x4 indicator will be illuminated.
  2. AWD locked - torque is supplied to the front and rear driveshaft constantly and the 4x4 indicator will stay illuminated in the instrument cluster (IC). This mode is not recommended for use on dry pavement or hard surfaces. AWD mode can be changed to AWD AUTO mode by pressing the message center SETUP button; the message AWD LOCKED will be displayed, press RESET within 4 seconds, the message AWD AUTO will be displayed and the 4x4 indicator will turn off.

If the transfer case begins to overheat, the system will default to the Auto Lock mode. The 4x4 indicator will illuminate in the IC. This condition may clear without any action being taken by the driver. The 4x4 indicator will turn off when the system cools down.

When a problem is detected in the AWD system, the powertrain malfunction indicator (wrench indicator) in the IC will illuminate.

Normal Operation

In order for the 4X4 control module to communicate with the scan tool, the operating voltage required to supply the 4X4 control module is in a range between 9 and 16 volts. Voltage is supplied at all times by circuit SBB26 (YE/RD). Run/Start voltage is supplied by circuit A_CBP18 (GY/OG).

Possible Causes

  1. CAN communication
  2. Scan tool
  3. Smart junction box (SJB) fuses: 4 (20A) 18 (10A)
  4. Power distribution box (PDB) fuse: 26 (20A)
  5. Power supply: Circuit SBB26 (YE/RD) Circuit A_CBP18 (GY/OG)
  6. Ground circuit GD145 (BK/BU)
  7. 4X4 control module
  8. Charging system

With the key in the ON position, the 4X4 control module receives the operator's choice of all wheel drive selection from the message center. The 4X4 control module then controls the electric clutch. If the transfer case is not responding to the operator's intentions, systematically check all inputs and outputs to the 4X4 control module.

Possible Causes

  1. 4x4 indicator
  2. Transfer case
  3. 4X4 control module
  4. Circuit: CCFO3 (GY/BN)
  5. Transfer case clutch
  6. Ignition switch and/or circuitry
  7. CAN communication network
  8. Instrument cluster (IC)

Scheme 1

Scheme 1: PINPOINT TEST B: THE VEHICLE DOES NOT SHIFT BETWEEN AWD AUTO AND AWD LOCKED CORRECTLY
Scheme 1: PINPOINT TEST B: THE VEHICLE DOES NOT SHIFT BETWEEN AWD AUTO AND AWD LOCKED CORRECTLY

Scheme 2

Scheme 2
Scheme 2
  1. B1 CHECK 4x4 INDICATOR PROVE-OUT Key in OFF position. Start the vehicle while observing the 4x4 indicator prove-out. Did the 4x4 indicator prove out? YES : Go to B2 . NO : CHECK the instrument cluster (IC) for faults. REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  2. B2 CHECK THE POWERTRAIN MALFUNCTION INDICATOR Start the engine. Observe the powertrain malfunction indicator. Does the powertrain malfunction indicator illuminate? YES : Go to B3 . NO : Go to B5 .
  3. B3 CARRY OUT THE ON-DEMAND SELF TEST Connect the diagnostic tool. Carry out the 4X4 control module on-demand self test. Does the self-test execute correctly? YES : Go to B4 . NO : Go to «Pinpoint Test A»(ref-270895-S39015584302007110700000) .
  4. B4 VERIFY THE DTCs Review the on-demand self test results. Did the 4X4 control module on-demand self test yield any DTCs. YES : Go to B5 . NO : CHECK the IC for faults. REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  5. B5 CHECK FOR 4x4 INDICATOR ILLUMINATION Select AWD LOCKED. Does the 4x4 indicator illuminate? YES : Go to B6 . NO : Go to B18 .
  6. B6 CHECK FOR WIND-UP IN AWD LOCKED MODE Drive the vehicle on a dry, hard surface in turns while applying the throttle. Is wind-up present in turns? YES : Go to B11 . NO : Go to B7 .
  7. B7 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated (PWM)) PID at wide open throttle (WOT), with the transfer case in AWD LOCKED mode, engine off, key on. Does the clutch duty cycle PID indicate 98% clutch at WOT? YES : Go to B8 . NO : Go to B10 .
  8. B8 CHECK FOR VOLTAGE ON CLUTCH POWER CIRCUIT CCF03 (GY/BN) Carefully back-probe transfer case C350-16 (early build vehicles) or C3146-2 (late build vehicles), circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Use the scan tool active commands to cycle the transfer case clutch to 98 percent. Is the voltage greater than 8.5 volts? YES : END the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : END the active command. Go to B9 .
  9. B9 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Key in OFF position. Disconnect: Transfer Case C350 (Early build vehicles) or Transfer Case C3146 (Late build vehicles) Disconnect: 4X4 Control Module C281a Measure the resistance between transfer case C350-16 (early build vehicles) or C3146-2 (late build vehicles) harness side, and 4X4 control module C281a-17 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . CHECK the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  10. B10 CHECK THE THROTTLE POSITION OUTPUT PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record from 4X4 control module menu Monitor the throttle position output PID. Slowly move throttle from closed throttle to WOT and observe the throttle position output PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : Go to B8 . NO : CHECK the throttle position sensor and/or PCM. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  11. B11 CHECK THE 4x4 INDICATOR IN AWD AUTO MODE Select AWD AUTO. Does the 4x4 indicator turn off? YES : Go to B12 . NO : Go to «Pinpoint Test C»(ref-270895-S23974927872007110700000) .
  12. B12 CHECK FOR WIND-UP IN 4x4 AUTO MODE Drive the vehicle on a dry, hard surface in turns while applying the throttle. Is wind-up present in turns? YES : Go to B13 . NO : The AWD drive system is operating correctly.
  13. B13 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated [PWM]) PID at closed throttle, engine off, key on. Does the PID indicate 2 to 4 percent clutch application at closed throttle? YES : Go to B14 . NO : Go to B16 .
  14. B14 CHECK VOLTAGE ON THE CLUTCH POWER CIRCUIT CCF03 (GY/BN) Use the scan tool active commands to energize the transfer case clutch to 4 percent. Back-probe transfer case C350-16 (early build vehicles) or C3146-2 (late build vehicles), circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Is the voltage approximately 0.48 volt? YES : END the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : END the active command. Go to B15 .
  15. B15 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Key in OFF position. Disconnect: Transfer Case C350 (Early build vehicles) or Transfer Case C3146 (Late build vehicles) Disconnect: 4X4 Control Module C281a Measure the resistance between transfer case C350-16 (early build vehicles) or C3146-2 (late build vehicles) harness side, and 4X4 control module C281a-17 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . CHECK the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  16. B16 CHECK THE WHEEL SPEED PIDs Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record While driving the vehicle at 30 km/h (18 mph), monitor the wheel speed PIDs. Compare the speedometer reading to the wheel speed PIDs. Do the wheel speed PIDs and speedometer speeds match within 1.5 km/h (1 mph)? YES : Go to B17 . NO : CHECK the ABS system for faults. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  17. B17 CHECK THE THROTTLE POSITION SENSOR PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Slowly move throttle from closed throttle to WOT and observe the throttle position sensor voltage PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : INSTALL a new 4X4 control module. REFER to «ELECTRONIC ENGINE CONTROLS»(ref-270955) . CHECK the system for normal operation. NO : CHECK the throttle position sensor and/or PCM for faults. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  18. B18 CHECK THE IGNITION SWITCH STATUS PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Key in ON position. Monitor the ignition switch status PID. Does the ignition switch position correspond with the ignition status PID? YES : Go to B19 . NO : CHECK the ignition switch circuit(s) and CAN communication network. REFER to «STARTING SYSTEM»(ref-270900) and «MODULE COMMUNICATIONS NETWORK»(ref-270934) .
  19. B19 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID WITH AWD LOCKED MODE SELECTED Monitor the clutch duty cycle PID while switching to AWD LOCKED. Does the clutch duty cycle value equal 10 percent? YES : CHECK the IC. REFER to «INSTRUMENT CLUSTER AND PANEL ILLUMINATION»(ref-270965) . NO : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation.

The four wheel drive (4WD) system status is transmitted to the instrument cluster (IC) from the 4X4 control module through the controller area network (CAN) to the powertrain malfunction indicator. A steady indicator displays if the vehicle is in AWD LOCKED mode, according to the driver selection. A 4WD system fault condition will illuminate the powertrain malfunction indicator. The powertrain malfunction indicator includes other general powertrain system failures. For information about CAN, refer to MODULE COMMUNICATIONS NETWORK .

Possible Causes

  1. Instrument cluster (IC)
  2. 4WD system fault
  3. CAN circuits
  4. 4X4 control module

In order for the all wheel drive (AWD) system to function correctly, tires and wheels must be the same size, be in good condition and the front and rear axle ratios must match.

Possible Causes

  1. Unmatched tire sizes
  2. Unequal amounts of tire wear
  3. Unequal tire inflation pressures
  4. Unmatched front and rear axle ratios

When the vehicle is operating in all-wheel drive (AWD) LOCKED mode, the front and rear driveshaft rotate at the same speed. The amount of traction the vehicle can achieve depends on the amount of traction each tire can establish with the road surface. In order for the AWD system to operate correctly, each wheel/tire assembly must have matching sizes, and the front and rear axle ratios must match.

Possible Causes

  1. 4x4 indicator
  2. 4X4 control module
  3. Transfer case and related components
  4. Wheel/tire assemblies

When the vehicle is operating in all wheel drive locked (AWD) LOCKED mode, the front and rear driveshaft rotate at the same speed. The amount of traction the vehicle can achieve depends on the amount of traction each tire can establish with the road surface. In order for the AWD system to operate correctly, each wheel/tire assembly must have matching sizes and the front and rear axle ratios must match.

Possible Causes

  1. Unmatched tire sizes
  2. Unequal amounts of tire wear
  3. Unequal tire inflation pressures
  4. Unmatched front and rear axle ratios

The vehicle is equipped with an automatic electronic-shift system that allows the operator to choose between 3 different four wheel drive (4WD) modes. The operator can switch between 4x4 AUTO and 4x4 HIGH modes at any speed below 88 km/h (55 mph). The operator can switch between 4x4 AUTO and 4x4 HIGH at any speed. To engage or disengage 4x4 LOW mode, the vehicle speed must be less than 3 km/h (2 mph) and the transmission must be in NEUTRAL.

Wheel slip is sensed by monitoring the average front and rear wheel speeds. Based on steering wheel angle (SWA), accelerator pedal position and wheel slip, a pulse width modulated (PWM) signal is transmitted to the transfer case as torque is required.

The 4X4 control module will provide the anti-lock brake system (ABS) with current clutch duty cycle and whether or not ABS may command the clutch duty cycle.

The brake subsystem sends the following information signals to the 4WD system

  1. Occurrences of brake events and failures. Refer to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  2. Steering wheel angle status. Refer to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  3. Wheel speeds. Refer to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .

A concern with any of the above listed brake system signals will affect operation of the 4WD system.

The accelerator pedal position output signal is provided to the 4X4 control module from the powertrain control module (PCM). This signal is used by the 4X4 control module in controlling the transfer case clutch. The transfer case shift motor sense plate, an integral part of the assembly, informs the 4X4 control module of the transfer case position.

The electric shift motor is mounted externally to the transfer case. It drives a rotary cam which moves the range fork within the transfer case between the HIGH range (4x4 AUTO and 4x4 HIGH modes) and low range (4x4 LOW) positions.

The 4X4 control module varies the torque sent to the front driveline by controlling the transfer case clutch. At rest and under cruising conditions, the 4X4 control module activates the transfer case clutch a minimum duty cycle (percentage of time the clutch is turned on), which allows for the slight difference between the front and rear driveshaft which normally occurs when negotiating a corner on dry pavement. Under any of the following conditions, the 4X4 control module will increase the duty cycle in order to prevent or control slip

  1. Slip is detected
  2. Transfer case shift motor contact plate position inputs A, B, C, D

Feature inputs

  1. Mode select switch (MSS)
  2. SWA
  3. Transmission range indicator (transmitted from the transmission control module [TCM])
  4. Wheel speed (transmitted from the ABS module)
  5. Accelerator pedal position information (transmitted from the PCM)

Feature outputs

  1. PWM signal to transfer case clutch
  2. 4WD message center indicators
  3. Transfer case shift motor outputs

Shifts between 4x4 AUTO mode and 4x4 HIGH modes can be made at any speed. Listed below are the inputs and outputs needed by the 4X4 control module to execute a change between these modes.

Feature inputs

  1. Accelerator pedal position information (transmitted from the PCM)
  2. MSS
  3. Transfer case shift motor encoder contact plate position inputs A, B, C, D
  4. Wheel speed (transmitted from ABS module)

Feature outputs

  1. Transfer case shift motor outputs
  2. 4WD message center indicators
  3. PWM signal to transfer case clutch

When shifting into or out of 4x4 LOW mode, the 4X4 control module requires that the vehicle speed is less than 3 km/h (2 mph) and the transmission is in NEUTRAL.

Feature inputs

  1. Accelerator pedal position information (transmitted from the PCM)
  2. MSS
  3. Transfer case shift motor encoder contact plate position inputs A, B, C, D
  4. Wheel speed (transmitted from ABS module)

Feature outputs

  1. Transfer case shift motor outputs
  2. 4WD message center indicators
  3. PWM signal to transfer case clutch

In order for the 4X4 control module to communicate with the scan tool, the operating voltage required to supply the 4X4 control module is in a range between 9 and 16 volts. Voltage is supplied at all times by circuit SBB26 (YE/RD). Run/Start voltage is supplied by circuit A_CBP18 (GY/OG).

Possible Causes

  1. CAN communication
  2. Scan tool
  3. Smart junction box (SJB) fuses: 4 (20A) 18 (10A)
  4. Power distribution box (PDB) fuse: 26 (20A)
  5. Power supply: Circuit SBB26 (YE/RD) Circuit A_CBP18 (GY/OG)
  6. Ground circuit GD145 (BK/BU)
  7. 4X4 control module
  8. Charging system

With the key in the ON position, the 4X4 control module receives the operator's choice of 4WD selection from the mode select switch (MSS). The 4X4 control module then controls the electric clutch and transfer case shift motor. If the transfer case is not responding to the operator's intentions, systematically check all inputs and outputs to the 4X4 control module.

Possible Causes

  1. 4WD indicators
  2. Transfer case
  3. 4X4 control module
  4. Circuits: RCF13 (WH/BN) CCF03 (GY/BN) CCF13 (WH/BU)
  5. Transfer case clutch
  6. Ignition switch and/or circuitry
  7. CAN communication network
  8. Instrument cluster (IC)

Scheme 3

Scheme 3: PINPOINT TEST H: THE VEHICLE DOES NOT SHIFT BETWEEN 4x4 AUTO AND 4x4 HIGH CORRECTLY
Scheme 3: PINPOINT TEST H: THE VEHICLE DOES NOT SHIFT BETWEEN 4x4 AUTO AND 4x4 HIGH CORRECTLY

Scheme 4

Scheme 4
Scheme 4

Scheme 5

Scheme 5
Scheme 5

Scheme 6

Scheme 6
Scheme 6

Scheme 7

Scheme 7
Scheme 7

Scheme 8

Scheme 8
Scheme 8
  1. H1 CHECK 4x4 INDICATORS PROVE-OUT Key in OFF position. Start the vehicle while observing the 4x4 indicators prove-out. Did the indicators prove out? YES : Go to H2 . NO : CHECK the instrument cluster (IC). REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  2. H2 CHECK THE POWERTRAIN MALFUNCTION INDICATOR Start the engine. Observe the powertrain malfunction indicator. Does the powertrain malfunction indicator illuminate? YES : Go to H3 . NO : Go to H4 .
  3. H3 CARRY OUT THE 4X4 CONTROL MODULE ON-DEMAND SELF TEST Connect the diagnostic tool. Carry out the 4X4 control module on-demand self test. Did the self test complete? YES : Go to H4 . NO : Go to «Pinpoint Test G»(ref-270895-S07346229672007110700000) .
  4. H4 REVIEW THE ON-DEMAND SELF TEST Review the on-demand self test results. Were DTCs retrieved? YES : Go to H5 . NO : CHECK the IC. REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  5. H5 CHECK FOR 4x4 INDICATOR ILLUMINATION Select 4x4 HIGH. Does the 4x4 indicator illuminate? YES : Go to H6 . NO : Go to H18 .
  6. H6 CHECK FOR WIND-UP IN 4x4 HIGH Drive the vehicle on a dry, hard surface in turns while applying the throttle. Is wind-up present in turns? YES : Go to H11 . NO : Go to H7 .
  7. H7 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated-[PWM]) PID at wide open throttle (WOT), with the transfer case in 4x4 HIGH, engine off, key on. Does the clutch duty cycle PID indicate 98 percent clutch at WOT? YES : Go to H8 . NO : Go to H10 .
  8. H8 CHECK FOR VOLTAGE ON THE CLUTCH POWER CIRCUIT CCF03 (GY/BN) DURING ACTIVE COMMAND Carefully back-probe transfer case C350-16, circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Use the scan tool active commands to cycle the transfer case clutch to 98 percent. Is the voltage greater than 8.5 volts? YES : END the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : END the active command. Go to H9 .
  9. H9 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Key in OFF position. Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281a Measure the resistance between transfer case C350-16 harness side, and 4X4 control module C281a-17 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  10. H10 CHECK THE THROTTLE POSITION OUTPUT PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record from 4X4 control module menu Monitor the throttle position output PID. Slowly move throttle from closed throttle to WOT and observe the throttle position output PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : Go to H8 . NO : CHECK the throttle position sensor and/or PCM. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  11. H11 CHECK THE 4x4 INDICATOR IN 4x4 AUTO Select 4x4 AUTO. Does the 4x4 indicator turn off? YES : Go to H12 . NO : Go to «Pinpoint Test J»(ref-270895-S06901644182007110700000) .
  12. H12 CHECK FOR WIND-UP IN 4x4 AUTO Drive the vehicle on a dry, hard surface in turns while applying the throttle. Is wind-up present in turns? YES : Go to H13 . NO : The 4WD drive system is operating correctly.
  13. H13 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated-[PWM]) PID at closed throttle, engine off, key on. Does the PID indicate 2 to 4 percent clutch application at closed throttle? YES : Go to H14 . NO : Go to H16 .
  14. H14 CHECK VOLTAGE ON THE CLUTCH POWER CIRCUIT CCF03 (GY/BN) Use the scan tool active commands to energize the transfer case clutch to 4 percent. Carefully back-probe transfer case C350-16, circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Is the voltage approximately 0.48 volt? YES : END the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : END the active command. Go to H15 .
  15. H15 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281a Measure the resistance between transfer case C350-16 harness side, and 4X4 control module C281a-17 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  16. H16 CHECK THE WHEEL SPEED PIDs Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record While driving the vehicle at 30 km/h (18 mph), monitor the wheel speed PIDs. Compare the speedometer reading to the wheel speed PIDs. Do the wheel speed PIDs and speedometer speeds match within 1.5 km/h (1 mph)? YES : Go to H17 . NO : CHECK the ABS system for faults. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  17. H17 CHECK THE THROTTLE POSITION SENSOR PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Slowly move throttle from closed throttle to WOT and observe the throttle position sensor voltage PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : CHECK the throttle position sensor and/or PCM for faults. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  18. H18 CHECK THE IGNITION SWITCH STATUS PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Key in ON position. Monitor the ignition switch status PID. Does the ignition switch position correspond with the ignition status PID? YES : Go to H19 . NO : CHECK the ignition switch circuit(s) and CAN communication network. REFER to «STARTING SYSTEM»(ref-270900) and «MODULE COMMUNICATIONS NETWORK»(ref-270934) .
  19. H19 CHECK THE MSS PID IN 4x4 HIGH Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the MSS PID while switching to 4x4 HIGH. Do the MSS PID indicate 4x4 HIGH? YES : Go to H20 . NO : Go to H21 .
  20. H20 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID WITH THE MSS IN 4x4 HIGH Monitor the clutch duty cycle PID while switching to 4x4 HIGH. Does the clutch duty cycle value equal 10 percent? YES : CHECK the IC. REFER to «INSTRUMENT CLUSTER»(ref-270940) . NO : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation.
  21. H21 CHECK THE MSS Key in OFF position. Disconnect: MSS C284 Measure the resistance between MSS C284-2, component side and C284-3, component side. Refer to the following chart: MSS Position Resistance (± 1 percent) 4x4 AUTO 39 ohms 4x4 HIGH 237 ohms 4x4 LOW 536 ohms Are the resistances within the specified values? YES : Go to H22 . NO : INSTALL a new MSS. REFER to «Mode Select Switch (MSS)»(ref-270895-S37054334532007110700000) .
  22. H22 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR AN OPEN Measure the resistance between MSS C284-2 harness side and 4X4 control module C281b-10 harness side, circuit RCF13 (WH/BN); measure the resistance between MSS C284-3 harness side and 4X4 control module C281b-16 harness side, circuit CCF13 (BU/BK). Are the resistances less than 5 ohms? YES : Go to H23 . NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
  23. H23 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the voltage between MSS C284-3, circuit CCF13 (WH/BU) and ground. Is voltage present? YES : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test. NO : Go to H24 .
  24. H24 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO GROUND Key in OFF position. Measure the resistance between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the resistance between MSS C284-3, circuit CCF13 (WH/BU) and ground. Is the resistance greater than 10,000 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.

With the key in the ON position, the 4X4 control module receives the operator's choice of four wheel drive selection from the mode select switch (MSS). The 4X4 control module then controls the electric clutch and transfer case shift motor. If the transfer case is not responding to the operator's intentions, systematically check all inputs and outputs to the 4X4 control module.

Possible Causes

  1. Power distribution box (PDB) fuses: 23 (20A) - transfer case shift motor 26 (20A) - 4X4 control module
  2. Smart junction box (SJB) fuse 18 (10A)
  3. 4x4 LOW indicator
  4. 4x4 LOW LED
  5. Mode select switch (MSS)
  6. Transfer case
  7. Transfer case shift motor
  8. 4X4 control module
  9. ABS module
  10. Circuit CCF03 (GY/BN)
  11. CAN

Scheme 9

Scheme 9
Scheme 9

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11

Scheme 12

Scheme 12
Scheme 12

Scheme 13

Scheme 13
Scheme 13

Scheme 14

Scheme 14
Scheme 14

Scheme 15

Scheme 15
Scheme 15

Scheme 16

Scheme 16
Scheme 16

Scheme 17

Scheme 17
Scheme 17

Scheme 18

Scheme 18
Scheme 18

Scheme 19

Scheme 19
Scheme 19

Scheme 20

Scheme 20
Scheme 20
  1. I1 CHECK FOR DTCs Key in ON position. Connect the diagnostic tool. Carry out the on-demand self test. Are DTCs retrieved? YES : If C1729, go to I27 . If C1970, go to I15 . If C1971, go to I16 . If P1812, go to I9 . If P1815, go to I12 . If P1849, P1853, P1857 or P1861, go to I26 . If P1867 or P1891, Go to I24 . NO : Go to I2 .
  2. I2 MONITOR THE 4x4 LOW LED SWITCH Select 4x4 LOW: press the brake pedal. vehicle at rest. transmission in NEUTRAL. Monitor the 4x4 LOW LED. Does the 4x4 LOW LED blink then stay illuminated? YES : Go to I3 . NO : Go to I4 .
  3. I3 VERIFY THE 4x4 LOW LED STATE Monitor the 4x4 LOW LED. Does the 4x4 LOW LED continue blinking? YES : Go to I4 . NO : Go to I8 .
  4. I4 VERIFY THE 4x4 LOW LED STATE Monitor the 4x4 LOW LED. Does the 4x4 LOW LED illuminate constantly? YES : Go to I5 . NO : Go to I17 .
  5. I5 MONITOR THE 4x4 LOW INDICATOR (CLUSTER) Monitor the 4x4 LOW instrument cluster (IC) indicator. Is the 4x4 LOW IC indicator illuminated? YES : Go to I6 . NO : CHECK the IC. REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  6. I6 CHECK FOR WIND-UP IN TURNS ON THROTTLE Drive the vehicle on a dry, hard surface, executing turns while applying the throttle. Is wind-up present? YES : Go to I7 . NO : Go to I18 .
  7. I7 CHECK FOR GEAR REDUCTION While driving the vehicle, monitor the engine rpm and vehicle speed. Does the engine rpm and vehicle speed indicate that the vehicle is in 4x4 LOW (high rpm at low vehicle speed)? YES : The system is functioning correctly. NO : Go to I22 .
  8. I8 CHECK THE IGNITION STATUS PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Key in ON position. Monitor the ignition status PID. Does the ignition switch position correspond with the ignition status PID? YES : Go to I9 . NO : CHECK the ignition switch circuit(s) and CAN communication network. REFER to «MODULE COMMUNICATIONS NETWORK»(ref-270934) .
  9. I9 CHECK THE MSS Key in OFF position. Disconnect: MSS C284 Measure the resistance between MSS C284-2, component side and C284-3, component side. Refer to the following chart: MSS Position Resistance (± 1 percent) 4x4 AUTO 39 ohms 4x4 HIGH 237 ohms 4x4 LOW 536 ohms Are the resistances within the specified values? YES : Go to I10 . NO : INSTALL a new MSS. REFER to «Mode Select Switch (MSS)»(ref-270895-S37054334532007110700000) .
  10. I10 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR AN OPEN Measure the resistance between MSS C284-2 and 4X4 control module C281b-10, circuit RCF13 (WH/BN); measure the resistance between MSS C284-3 and 4X4 control module C281b-16, circuit CCF13 (WH/BU). Are the resistances less than 5 ohms? YES : Go to I11 . NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
  11. I11 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the voltage between MSS C284-3, circuit CCF13 (WH/BU) and ground. Is voltage present? YES : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test. NO : Go to I12 .
  12. I12 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO GROUND Measure the resistance between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the resistance between MSS C284-3, circuit CCF13 (WH/BU) and ground. Are the resistances greater than 10,000 ohms? YES : Go to I13 . NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
  13. I13 CHECK MSS LED CIRCUIT A_CBP18 (GY/OG) FOR VOLTAGE Key in ON position. Measure the voltage between MSS C284-5, circuit A_CBP18 (GY/OG) and ground. Is the voltage greater than 8 volts? YES : Go to I14 . NO : REPAIR the circuit. TEST the system for normal operation.
  14. I14 CHECK MSS LED CIRCUIT CCF06 (BU/GN) FOR AN OPEN Key in OFF position. Measure the resistance between MSS C284-6 and 4X4 control module C281b-5, circuit CCF06 (BU/GN). Is the resistance less than 5 ohms? YES : Go to I15 . NO : REPAIR the circuit. TEST the system for normal operation.
  15. I15 CHECK MSS LED CIRCUIT CCF06 (BU/GN) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between MSS C284-6, circuit CCF06 (BU/GN) and ground. Is voltage present? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. NO : Go to I16 .
  16. I16 CHECK MSS LED CIRCUIT CCF06 (BU/GN) FOR A SHORT TO GROUND Key in ON position. Measure the resistance between MSS C284-6, circuit CCF06 (BU/GN) and ground. Is the resistance greater than 10,000 ohms? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. NO : INSTALL a new MSS. REFER to «Mode Select Switch (MSS)»(ref-270895-S37054334532007110700000) . CLEAR the DTCs. REPEAT the self test.
  17. I17 CHECK THE TRANSMISSION RANGE (TR), BRAKE ON/OFF (BOO) AND SHAFT SPEED PIDs DURING 4x4 LOW SHIFT Connect the diagnostic tool. Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record A. Monitor the 4X4 control module transmission range (TR) sensor status PID while shifting the transmission through gear ranges. B. Monitor the 4X4 control module brake ON/OFF (BOO) switch PID while pressing and releasing the brake pedal. C. Monitor the 4X4 control module shaft speed PIDs. A. Does the 4X4 control module transmission range (TR) sensor PID indicate NEUTRAL when the transmission is shifted to NEUTRAL? B. Does the BOO switch PID agree with the actual brake pedal positions? C. Do the shaft speed PIDs indicate 0 km/h (0 mph)? YES : If all 3 PIDs are accurate, go to I24 . NO : A. REFER to «AUTOMATIC TRANSAXLE/TRANSMISSION - 5R55S»(ref-270891) or «AUTOMATIC TRANSAXLE/TRANSMISSION - 6R60»(ref-270910) for further diagnosis of the TR sensor and the CAN communication network. B. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) for further diagnosis of the BOO switch and the CAN communication network. C. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) for further diagnosis of the ABS system and the CAN communication network.
  18. I18 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated-[PWM]) PID at wide open throttle (WOT), with the transfer case in 4x4 LOW, engine off, key on. Does the clutch duty cycle PID indicate 98 percent clutch application at WOT? YES : Go to I19 . NO : Go to I21 .
  19. I19 CHECK FOR VOLTAGE ON THE CLUTCH POWER CIRCUIT CCF03 (GY/BN) Carefully back-probe the transfer case connector C350-16, circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Use the scan tool active commands to cycle the transfer case clutch to 98 percent. Is the voltage greater than 9 volts? YES : End the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : End the active command. Go to I20 .
  20. I20 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281a Measure the resistance between transfer case connector C350-16 harness side, and 4X4 control module C281-17 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  21. I21 CHECK THE 4X4 CONTROL MODULE THROTTLE POSITION OUTPUT PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the 4X4 control module throttle position output PID. Slowly move throttle from closed throttle to WOT and observe the throttle position sensor PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : CHECK the CAN communication network. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  22. I22 CHECK THE CONTACT PLATE ENCODER PIDs IN 4x4 LOW Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record With the MSS in 4x4 LOW, monitor the contact plate position PIDs. Refer to the following chart: Contact Plate Position PID MSS PID 4WD AUTO/4H MSS PID 4L PLATE_A CLOSED OPEN PLATE_B OPEN CLOSED PLATE_C CLOSED OPEN PLATE_D CLOSED CLOSED Do the contact plate position PIDs indicate that the transfer case shift motor is in 4x4 LOW? YES : Go to I23 . NO : Go to I24 .
  23. I23 CHECK THE TRANSFER CASE SHIFT MOTOR Remove the transfer case shift motor from the transfer case. Rotate the shift cam through all positions. Does the transfer case shift cam rotate with difficulty (is the force required to rotate the cam greater than 45 N.m [33 lb-ft])? YES : REPAIR the transfer case. REFER to «TRANSFER CASE»(ref-270918) . CLEAR the DTCs. REPEAT the self-test. NO : INSTALL a new transfer case shift motor. REFER to «Transfer Case Shift Motor»(ref-270895-S39721475852007110700000) . CLEAR the DTCs. REPEAT the self-test.
  24. I24 CHECK CIRCUITS RCF09 (BN/WH), CCF17 (WH/OG), CCF16 (VT/GN), CCF15 (BN/YE) AND CCF14 (GN/OG) FOR AN OPEN Key in OFF position. Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281a Measure the resistance of the following circuits between 4X4 control module C281a, harness side and transfer case C350, harness side: Circuit C281a C350 RCF09 (BN/WH) 3 10 CCF17 (WH/OG) 4 13 CCF16 (VT/GN) 5 9 CCF15 (BN/YE) 6 1 CCF14 (GN/OG) 7 5 Are the resistances less than 5 ohms? YES : Go to I25 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  25. I25 CHECK CIRCUITS RCF09 (BN/WH), CCF17 (WH/OG), CCF16 (VT/GN), CCF15 (BN/YE) AND CCF14 (GN/OG) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between the following circuits at the 4X4 control module C281a, harness side and ground: Circuit C281a RCF09 (BN/WH) 3 CCF17 (WH/OG) 4 CCF16 (VT/GN) 5 CCF15 (BN/YE) 6 CCF14 (GN/OG) 7 Is voltage present? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. NO : Go to I26 .
  26. I26 CHECK CIRCUITS RCF09 (BN/WH), CCF17 (WH/OG), CCF16 (VT/GN), CCF15 (BN/YE) AND CCF14 (GN/OG) FOR A SHORT TO GROUND Key in OFF position. Measure the resistance between the following circuits at 4X4 control module C281a, harness side and ground: Circuit C281a RCF09 (BN/WH) 3 CCF17 (WH/OG) 4 CCF16 (VT/GN) 5 CCF15 (BN/YE) 6 CCF14 (GN/OG) 7 Are the resistances greater than 10,000 ohms? YES : Go to I27 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  27. I27 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR POWER DURING ACTIVE COMMANDS Connect: 4X4 Control Module C281a Enter the following diagnostic mode on the diagnostic tool: Access Active Commands Enter the clockwise transfer case shift motor active command ON and OFF and measure the voltage between transfer case C350-15, circuit CCF07 (GN/RD) harness side and ground. Enter the counterclockwise transfer case shift motor active command ON and OFF and measure the voltage between transfer case C350-14, circuit CCF08 (GY/OG) harness side and ground. Are the voltages 10 volts or greater while the corresponding active commands are on? YES : INSTALL a new transfer case shift motor. CLEAR the DTCs. REPEAT the self-test. NO : Go to I28 .
  28. I28 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR AN OPEN Measure the resistance between transfer case C350-14, circuit and 4X4 control module C281a-2, harness side, circuit CCF08 (GY/OG). Measure the resistance between transfer case C350-15, circuit and 4X4 control module C281a-9, harness side, circuit CCF07 (BN/GN). Are the resistances less than 5 ohms? YES : Go to I29 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. Go to «Pinpoint Test N»(ref-270895-S29623263522007110700000) .
  29. I29 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR A SHORT TO VOLTAGE Measure the voltage between 4X4 control module C281a-2, circuit CCF08 (GY/OG), harness side and ground. Measure the resistance between 4X4 control module C281a-9, circuit CCF07 (BN/GN), harness side and ground. Is voltage present? YES : Go to I30 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. Go to «Pinpoint Test N»(ref-270895-S29623263522007110700000) .
  30. I30 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR A SHORT TO GROUND Measure the resistance between 4X4 control module C281a-2, circuit CCF08 (GY/OG) harness side and ground. Measure the resistance between 4X4 control module C281a-9, circuit CCF07 (BN/GN) harness side and ground. Are the resistances greater than 10,000 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . Go to «Pinpoint Test N»(ref-270895-S29623263522007110700000) . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. Go to «Pinpoint Test N»(ref-270895-S29623263522007110700000) .

The 4x4 HIGH indicator status is transmitted to the instrument cluster (IC) from the 4X4 control module through the controller area network (CAN). A steady indicator displays whether the vehicle is in 4x4 LOW or 4x4 HIGH, according to the driver selection. A 4WD system fault will cause the powertrain malfunction indicator to illuminate when a 4WD system fault condition has been detected. This light also indicates other general powertrain failures.

Possible Causes

  1. Instrument cluster (IC)
  2. 4WD system fault
  3. CAN circuits
  4. 4X4 control module

In order for the four wheel drive (4WD) system to function correctly, tires and wheels must be the same size, be in good condition and the front and rear axle ratios must match.

Possible Causes

  1. Unmatched tire sizes
  2. Unequal amounts of tire wear
  3. Unequal tire inflation pressures
  4. Unmatched front and rear axle ratios

When the vehicle is operating in 4x4 AUTO, all 4 wheels receive the same amount of torque and rotate at the same speed. The amount of traction the vehicle can achieve depends on the amount of traction each tire can establish with the road surface. In order for the four wheel drive (4WD) system to function correctly, each tire must be in good condition and the front and rear axle ratios must match.

Possible Causes

  1. Unmatched tire sizes
  2. Unequal amounts of tire wear
  3. Unequal tire inflation pressures
  4. Unmatched front and rear axle ratios

Neutral tow is a dealer-installed option that allows the vehicle to be towed with the 4 road wheels without damaging the transmission. Neutral tow operates by disengaging the transmission from the rear differential.

Possible Causes

  1. Neutral tow indicator
  2. CAN circuits
  3. Vehicle security module (VSM)
  4. 4.0L digital transmission range (TR) sensor
  5. 4.6L neutral shifter position sensor
  6. Brake ON/OFF (BOO) switch
  7. Door ajar switch
  8. Ignition switch/circuitry

When the vehicle is operating in 4x4 HIGH or 4x4 LOW, (4H/4L), all 4 wheels rotate at the same speed. The amount of traction the vehicle can achieve depends on the amount of traction each tire can establish with the road surface. In order for the 4WD system to operate correctly, each wheel/tire assembly must have matching sizes and the front and rear axle ratios must match.

Possible Causes

  1. 4x4 indicators
  2. 4X4 control module
  3. Transfer case and related components
  4. Wheel/tire assemblies

The vehicle is equipped with an automatic electronic-shift system that allows the operator to choose between 3 different four wheel drive (4WD) modes. The operator can switch between 4x4 AUTO and 4x4 HIGH modes at any speed below 88 km/h (55 mph). The operator can switch between 4x4 AUTO and 4x4 HIGH at any speed. To engage or disengage 4x4 LOW modes, the vehicle speed must be less than 3 km/h (2 mph) and the transmission must be in NEUTRAL.

Wheel slip is sensed by monitoring the average front and rear wheel speeds. Based on steering wheel angle (SWA), accelerator pedal position and wheel slip, a pulse width modulated (PWM) signal is transmitted to the transfer case as torque is required.

The 4X4 control module will provide the anti-lock brake system (ABS) with current clutch duty cycle and whether or not ABS may command the clutch duty cycle.

The brake subsystem sends the following information signals to the 4WD system

  1. Occurrences of brake events and failures. Refer to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  2. Steering wheel angle status. Refer to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  3. Wheel speeds. Refer to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .

A concern with any of the above listed brake system signals will affect operation of the 4WD system.

The accelerator pedal position output signal is provided to the 4X4 control module from the powertrain control module (PCM). This signal is used by the 4X4 control module in controlling the transfer case clutch. The transfer case shift motor sense plate, an integral part of the assembly, informs the 4X4 control module of the transfer case position.

The electric shift motor is mounted externally to the transfer case. It drives a rotary cam which moves the range fork within the transfer case between the HIGH range (4x4 AUTO and 4x4 HIGH modes) and low range (4x4 LOW) positions.

The 4X4 control module varies the torque sent to the front driveline by controlling the transfer case clutch. At rest and under cruising conditions, the 4X4 control module activates the transfer case clutch a minimum duty cycle (percentage of time the clutch is turned on), which allows for the slight difference between the front and rear driveshaft which normally occurs when negotiating a corner on dry pavement. Under any of the following conditions, the 4X4 control module will increase the duty cycle in order to prevent or control slip.

  1. Slip is detected
  2. Transfer case shift motor contact plate position inputs A, B, C, D

Feature inputs

  1. Mode select switch (MSS)
  2. SWA
  3. Transmission range indicator (transmitted from the transmission control module [TCM])
  4. Wheel speed (transmitted from the ABS module )
  5. Accelerator pedal position information (transmitted from the PCM)

Feature outputs

  1. PWM signal to transfer case clutch
  2. 4WD message center indicators
  3. Transfer case shift motor outputs

Shifts between 4x4 AUTO mode and 4x4 HIGH modes can be made at any speed. Listed below are the inputs and outputs needed by the 4X4 control module to execute a change between any of these modes.

Feature inputs

  1. Accelerator pedal position information (transmitted from the PCM)
  2. MSS
  3. Transfer case shift motor encoder contact plate position inputs A, B, C, D
  4. Wheel speed (transmitted from ABS module)

Feature outputs

  1. Transfer case shift motor outputs
  2. 4WD message center indicators
  3. PWM signal to transfer case clutch

When shifting into or out of 4x4 LOW mode, the 4X4 control module requires that the vehicle speed is less than 3 km/h (2 mph) and the transmission is in NEUTRAL.

Feature inputs

  1. Accelerator pedal position information (transmitted from the PCM)
  2. MSS
  3. Transfer case shift motor encoder contact plate position inputs A, B, C, D
  4. Wheel speed signal (transmitted from ABS module)

Feature outputs

  1. Transfer case shift motor outputs
  2. 4WD message center indicators
  3. PWM signal to transfer case clutch

In order for the 4X4 control module to communicate with the scan tool, the operating voltage required to supply the 4X4 control module is in a range between 9 and 16 volts. Voltage is supplied at all times by circuit SBB26 (YE/RD). Run/Start voltage is supplied by circuit A_CBP18 (GY/OG).

Possible Causes

  1. CAN communication
  2. Scan tool
  3. Smart junction box (SJB) fuses: 4 (20A) 18 (10A)
  4. Power distribution box (PDB) fuse: 26 (20A)
  5. Power supply: Circuit SBB26 (YE/RD) Circuit A_CBP18 (GY/OG)
  6. Ground circuit GD145 (BK/BU)
  7. 4X4 control module
  8. Charging system

With the key in the ON position, the 4X4 control module receives the operator's choice of 4WD selection from the mode select switch (MSS). The 4X4 control module then controls the electric clutch and transfer case shift motor. If the transfer case is not responding to the operator's intentions, systematically check all inputs and outputs to the 4X4 control module.

Possible Causes

  1. 4x4 indicators
  2. Transfer case
  3. 4X4 control module
  4. Circuits: RCF13 (WH/BN) CCF03 (GY/BN) CCF13 (WH/BU)
  5. Transfer case clutch
  6. Ignition switch and/or circuitry
  7. CAN communication network
  8. Instrument cluster (IC)

Scheme 21

Scheme 21
Scheme 21

Scheme 22

Scheme 22
Scheme 22
  1. P1 CHECK THE 4x4 INDICATORS PROVE-OUT Key in OFF position. Start the vehicle while observing the 4x4 indicators prove-out. Did the indicators prove out? YES : Go to P2 . NO : CHECK the instrument cluster (IC). REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  2. P2 CHECK THE POWERTRAIN MALFUNCTION INDICATOR Start the engine. Observe the powertrain malfunction indicator. Does the powertrain malfunction indicator illuminate? YES : Go to P3 . NO : Go to P4 .
  3. P3 CARRY OUT THE 4X4 CONTROL MODULE ON-DEMAND SELF TEST Connect the diagnostic tool. Carry out the 4X4 control module on-demand self test. Did the self test complete? YES : Go to P4 . NO : Go to «Pinpoint Test O»(ref-270895-S20877592432007110700000) .
  4. P4 REVIEW THE ON-DEMAND SELF TEST Review the on-demand self test results. Were DTCs retrieved? YES : Go to P5 . NO : CHECK the IC. REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  5. P5 CHECK FOR 4x4 INDICATOR ILLUMINATION Select 4x4 HIGH. Does the 4x4 indicator illuminate? YES : Go to P6 . NO : Go to P18 .
  6. P6 CHECK FOR WIND-UP IN 4x4 HIGH Drive the vehicle on a dry, hard surface in turns while applying the throttle. Is wind-up present in turns? YES : Go to P11 . NO : Go to P7 .
  7. P7 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated-[PWM]) PID at wide open throttle (WOT), with the transfer case in 4x4 HIGH, engine off, key on. Does the clutch duty cycle PID indicate 98 percent clutch at WOT? YES : Go to P8 . NO : Go to P10 .
  8. P8 CHECK FOR VOLTAGE ON CLUTCH POWER CIRCUIT CCF03 (GY/BN) DURING ACTIVE COMMAND Carefully back-probe transfer case C350-16, circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multi-meter. Use the scan tool active commands to cycle the transfer case clutch to 98 percent. Is the voltage greater than 8.5 volts? YES : END the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : End the active command. Go to P9 .
  9. P9 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Key in OFF position. Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281b Measure the resistance between transfer case C350-16 harness side, and 4X4 control module C281b-1 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  10. P10 CHECK THE THROTTLE POSITION OUTPUT PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record from 4X4 control module menu. Monitor the throttle position output PID. Slowly move throttle from closed throttle to WOT and observe the throttle position output PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : Go to P8 . NO : CHECK the throttle position sensor and/or PCM. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  11. P11 CHECK THE 4x4 INDICATOR IN 4x4 AUTO Select 4x4 AUTO. Does the 4x4 indicator turn off? YES : Go to P12 . NO : Go to «Pinpoint Test R»(ref-270895-S14831702882007110700000) .
  12. P12 CHECK FOR WIND-UP IN 4x4 AUTO Drive the vehicle on a dry, hard surface in turns while applying the throttle. Is wind-up present in turns? YES : Go to P13 . NO : The 4WD drive system is operating correctly.
  13. P13 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated-[PWM]) PID at closed throttle, engine off, key on. Does the PID indicate 2 to 4 percent clutch application at closed throttle? YES : Go to P14 . NO : Go to P16 .
  14. P14 CHECK THE VOLTAGE ON CLUTCH POWER CIRCUIT CCF03 (GY/BN) Use the scan tool active commands to energize the transfer case clutch to 4 percent. Carefully back-probe transfer case C350-16, circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Is the voltage approximately 0.48 volt? YES : END the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : END the active command. Go to P15 .
  15. P15 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281a Measure the resistance between transfer case C350-16 harness side, and 4X4 control module C281b-1 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  16. P16 CHECK THE WHEEL SPEED PIDs Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record While driving the vehicle at 30 km/h (18 mph), monitor the wheel speed PIDs. Compare the speedometer reading to the wheel speed PIDs. Do the wheel speed PIDs and speedometer speeds match within 1.5 km/h (1 mph)? YES : Go to P17 . NO : CHECK the ABS system for faults. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) .
  17. P17 CHECK THE THROTTLE POSITION SENSOR PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Slowly move throttle from closed throttle to WOT and observe the throttle position sensor voltage PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : CHECK the throttle position sensor and/or PCM for faults. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  18. P18 CHECK THE IGNITION SWITCH STATUS PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Key in ON position. Monitor the ignition switch status PID. Does the ignition switch position correspond with the ignition status PID? YES : Go to P19 . NO : CHECK the ignition switch circuit(s) and CAN communication network. REFER to «STARTING SYSTEM»(ref-270900) and «MODULE COMMUNICATIONS NETWORK»(ref-270934) .
  19. P19 CHECK THE MSS PID IN 4x4 HIGH Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the MSS PID while switching to 4x4 HIGH. Do the MSS PID indicate 4x4 HIGH? YES : Go to P20 . NO : Go to P21 .
  20. P20 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID WITH THE MSS IN 4x4 HIGH Monitor the clutch duty cycle PID while switching to 4x4 HIGH. Does the clutch duty cycle value equal 10 percent? YES : CHECK the IC. REFER to «INSTRUMENT CLUSTER»(ref-270940) . NO : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation.
  21. P21 CHECK THE MSS Key in OFF position. Disconnect: MSS C284 Measure the resistance between MSS C284-2, component side and C284-3, component side. Refer to the following chart: MSS Position Resistance (± 1 percent) 4x4 AUTO 39 ohms 4x4 HIGH 237 ohms 4x4 LOW 536 ohms Are the resistances within the specified values? YES : Go to P22 . NO : INSTALL a new MSS. REFER to «Mode Select Switch (MSS)»(ref-270895-S37054334532007110700000) .
  22. P22 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR AN OPEN Measure the resistance between MSS C284-2 harness side and 4X4 control module C281a-20 harness side, circuit RCF13 (WH/BN); measure the resistance between MSS C284-3 harness side and 4X4 control module C281a-11 harness side, circuit CCF13 (BU/BK). Are the resistances less than 5 ohms? YES : Go to P23 . NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
  23. P23 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the voltage between MSS C284-3, circuit CCF13 (WH/BU) and ground. Is voltage present? YES : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test. NO : Go to P24 .
  24. P24 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO GROUND Key in OFF position. Measure the resistance between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the resistance between MSS C284-3, circuit CCF13 (WH/BU) and ground. Is the resistance greater than 10,000 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.

With the key in the ON position, the 4X4 control module receives the operator's choice of 4WD selection from the mode select switch (MSS). The 4X4 control module then controls the electric clutch and transfer case shift motor. If the transfer case is not responding to the operator's intentions, systematically check all inputs and outputs to the 4X4 control module.

Possible Causes

  1. Power distribution box (PDB) fuses: 23 (20A) - transfer case shift motor 26 (20A) - 4X4 control module
  2. Smart junction box (SJB) fuse 18 (10A)
  3. 4x4 LOW indicator
  4. 4x4 LOW LED
  5. Mode select switch (MSS)
  6. Transfer case
  7. Transfer case shift motor
  8. 4X4 control module
  9. ABS module
  10. Circuit CCF03 (GY/BN)
  11. CAN

Scheme 23

Scheme 23
Scheme 23

Scheme 24

Scheme 24
Scheme 24

Scheme 25

Scheme 25
Scheme 25

Scheme 26

Scheme 26
Scheme 26

Scheme 27

Scheme 27
Scheme 27

Scheme 28

Scheme 28
Scheme 28

Scheme 29

Scheme 29
Scheme 29
  1. Q1 CHECK FOR DTCs Key in ON position. Connect the diagnostic tool. Carry out the on-demand self test. Are DTCs retrieved? YES : If C1729, go to Q27 . If C1970, go to Q15 . If C1971, go to Q16 . If P1812, go to Q9 . If P1815, go to Q12 . If P1849, P1853, P1857 or P1861, go to Q26 . If P1867 or P1891, Go to Q24 . NO : Go to Q2 .
  2. Q2 MONITOR THE 4x4 LOW LED SWITCH Select 4x4 LOW: press the brake pedal. vehicle at rest. transmission in N (neutral). Monitor the 4x4 LOW LED. Does the 4x4 LOW LED blink then stay illuminated? YES : Go to Q3 . NO : Go to Q4 .
  3. Q3 VERIFY THE 4x4 LOW LED STATE Monitor the 4x4 LOW LED. Does the 4x4 LOW LED continue blinking? YES : Go to Q4 . NO : Go to Q8 .
  4. Q4 VERIFY THE 4x4 LOW LED STATE Monitor the 4x4 LOW LED. Does the 4x4 LOW LED illuminate constantly? YES : Go to Q5 . NO : Go to Q17 .
  5. Q5 MONITOR THE 4x4 LOW INDICATOR (CLUSTER) Monitor the 4x4 LOW instrument cluster (IC) indicator. Is the 4x4 LOW IC indicator illuminated? YES : Go to Q6 . NO : CHECK the IC. REFER to «INSTRUMENT CLUSTER»(ref-270940) .
  6. Q6 CHECK FOR WIND-UP IN TURNS ON THROTTLE Drive the vehicle on a dry, hard surface, executing turns while applying the throttle. Is wind-up present? YES : Go to Q7 . NO : Go to Q18 .
  7. Q7 CHECK FOR GEAR REDUCTION While driving the vehicle, monitor the engine rpm and vehicle speed. Does the engine rpm and vehicle speed indicate that the vehicle is in 4x4 LOW (high rpm at low vehicle speed)? YES : The system is functioning correctly. NO : Go to Q22 .
  8. Q8 CHECK THE IGNITION STATUS PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Key in ON position. Monitor the ignition status PID. Does the ignition switch position correspond with the ignition status PID? YES : Go to Q9 . NO : CHECK the ignition switch circuit(s) and CAN communication network. REFER to «MODULE COMMUNICATIONS NETWORK»(ref-270934) .
  9. Q9 CHECK THE MSS Key in OFF position. Disconnect: MSS C284 Measure the resistance between MSS C284-2, component side and C284-3, component side. Refer to the following chart: MSS Position Resistance (± 1 percent) 4x4 AUTO 39 ohms 4x4 HIGH 237 ohms 4x4 LOW 536 ohms Are the resistances within the specified values? YES : Go to Q10 . NO : INSTALL a new MSS. REFER to «Mode Select Switch (MSS)»(ref-270895-S37054334532007110700000) .
  10. Q10 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR AN OPEN Measure the resistance between MSS C284-2 harness side and 4X4 control module C281a-20 harness side, circuit RCF13 (WH/BN); measure the resistance between MSS C284-3 harness side and 4X4 control module C281a-11 harness side, circuit CCF13 (BU/BK). Are the resistances less than 5 ohms? YES : Go to Q11 . NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
  11. Q11 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the voltage between MSS C284-3, circuit CCF13 (WH/BU) and ground. Is voltage present? YES : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test. NO : Go to Q12 .
  12. Q12 CHECK MSS CIRCUITS RCF13 (WH/BN) AND CCF13 (WH/BU) FOR A SHORT TO GROUND Measure the resistance between MSS C284-2, circuit RCF13 (WH/BN) and ground; measure the resistance between MSS C284-3, circuit CCF13 (WH/BU) and ground. Are the resistances greater than 10,000 ohms? YES : Go to Q13 . NO : REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
  13. Q13 CHECK MSS LED CIRCUIT A_CBP18 (GY/OG) FOR VOLTAGE Key in ON position. Measure the voltage between MSS C284-5, circuit A_CBP18 (GY/OG) and ground. Is the voltage greater than 8 volts? YES : Go to Q14 . NO : REPAIR the circuit. TEST the system for normal operation.
  14. Q14 CHECK MSS LED CIRCUIT CCF06 (BU/GN) FOR AN OPEN Key in OFF position. Measure the resistance between MSS C284-6 and 4X4 control module C281a-18, circuit CCF06 (BU/GN). Is the resistance less than 5 ohms? YES : Go to Q15 . NO : REPAIR the circuit. TEST the system for normal operation.
  15. Q15 CHECK MSS LED CIRCUIT CCF06 (BU/GN) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between MSS C284-6, circuit CCF06 (BU/GN) and ground. Is voltage present? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. NO : Go to Q16 .
  16. Q16 CHECK MSS LED CIRCUIT CCF06 (BU/GN) FOR A SHORT TO GROUND Key in ON position. Measure the resistance between MSS C284-6, circuit CCF06 (BU/GN) and ground. Is the resistance greater than 10,000 ohms? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. NO : INSTALL a new MSS. REFER to «Mode Select Switch (MSS)»(ref-270895-S37054334532007110700000) . CLEAR the DTCs. REPEAT the self test.
  17. Q17 CHECK THE TRANSMISSION RANGE (TR), BRAKE ON/OFF (BOO) AND SHAFT SPEED PIDs DURING 4x4 LOW SHIFT Connect the diagnostic tool. Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record A. Monitor the 4X4 control module transmission range (TR) sensor status PID while shifting the transmission through gear ranges. B. Monitor the 4X4 control module brake ON/OFF (BOO) switch PID while pressing and releasing the brake pedal. C. Monitor the 4X4 control module shaft speed PIDs. A. Does the 4X4 control module transmission range (TR) sensor PID indicate NEUTRAL when the transmission is shifted to NEUTRAL? B. Does the BOO switch PID agree with the actual brake pedal positions? C. Do the shaft speed PIDs indicate 0 km/h (0 mph)? YES : If all 3 PIDs are accurate, go to Q24 . NO : A. REFER to «AUTOMATIC TRANSAXLE/TRANSMISSION - 5R55S»(ref-270891) or «AUTOMATIC TRANSAXLE/TRANSMISSION - 6R60»(ref-270910) for further diagnosis of the TR sensor and the CAN communication network. B. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) for further diagnosis of the BOO switch and the CAN communication network. C. REFER to «VEHICLE DYNAMIC SYSTEMS»(ref-270960) for further diagnosis of the ABS system and the CAN communication network.
  18. Q18 CHECK THE TRANSFER CASE CLUTCH DUTY CYCLE PID Key in ON position. Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the transfer case clutch duty cycle (pulse width modulated-[PWM]) PID at wide open throttle (WOT), with the transfer case in 4x4 LOW, engine off, key on. Does the clutch duty cycle PID indicate 98 percent clutch application at WOT? YES : Go to Q19 . NO : Go to Q21 .
  19. Q19 CHECK FOR VOLTAGE ON CLUTCH POWER CIRCUIT CCF03 (GY/BN) Carefully back-probe the transfer case connector C350-16, circuit CCF03 (GY/BN). Measure the voltage on circuit CCF03 (GY/BN) using a digital multimeter. Use the scan tool active commands to cycle the transfer case clutch to 98 percent. Is the voltage greater than 9 volts? YES : End the active command. CHECK the transfer case. REFER to «TRANSFER CASE»(ref-270918) . NO : End the active command. Go to Q20 .
  20. Q20 CHECK CIRCUIT CCF03 (GY/BN) FOR AN OPEN Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281b Measure the resistance between transfer case C350-16 harness side, and 4X4 control module C281b-1 harness side, circuit CCF03 (GY/BN). Is the resistance less than 5 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : REPAIR the circuit. CHECK the system for normal operation.
  21. Q21 CHECK THE 4X4 CONTROL MODULE THROTTLE POSITION OUTPUT PID Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record Monitor the 4X4 control module throttle position output PID. Slowly move throttle from closed throttle to WOT and observe the throttle position sensor PID. Does the value vary between 0 percent at closed throttle and 100 percent at WOT? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . TEST the system for normal operation. NO : CHECK the CAN communication network. REFER to the «Introduction - Gasoline Engines»(ref-268480) .
  22. Q22 CHECK THE CONTACT PLATE ENCODER PIDs IN 4x4 LOW Enter the following diagnostic mode on the diagnostic tool: PID/DATA Monitor and Record With the MSS in 4x4 LOW, monitor the contact plate position PIDs. Refer to the following chart: Contact Plate Position PID MSS PID 4WD AUTO/4H MSS PID 4L PLATE_A CLOSED OPEN PLATE_B OPEN CLOSED PLATE_C CLOSED OPEN PLATE_D CLOSED CLOSED Do the contact plate position PIDs indicate that the transfer case shift motor is in 4x4 LOW? YES : Go to Q23 . NO : Go to Q24 .
  23. Q23 CHECK THE TRANSFER CASE SHIFT MOTOR Remove the transfer case shift motor from the transfer case. Rotate the shift cam through all positions. Does the transfer case shift cam rotate with difficulty (is the force required to rotate the cam greater than 45 N.m [33 lb-ft])? YES : REPAIR the transfer case. REFER to «TRANSFER CASE»(ref-270918) . CLEAR the DTCs. REPEAT the self-test. NO : INSTALL a new transfer case shift motor. REFER to «Transfer Case Shift Motor»(ref-270895-S39721475852007110700000) . CLEAR the DTCs. REPEAT the self-test.
  24. Q24 CHECK CIRCUITS RCF09 (BN/WH), CCF17 (WH/OG), CCF16 (VT/GN), CCF15 (BN/YE) AND CCF14 (GN/OG) FOR AN OPEN Key in OFF position. Disconnect: Transfer Case C350 Disconnect: 4X4 Control Module C281a Measure the resistance of the following circuits between 4X4 control module C281a, harness side and transfer case C350, harness side: Circuit C281a C350 RCF09 (BN/WH) 16 10 CCF17 (WH/OG) 4 13 CCF16 (VT/GN) 3 9 CCF15 (BN/YE) 2 1 CCF14 (GN/OG) 1 5 Are the resistances less than 5 ohms? YES : Go to Q25 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  25. Q25 CHECK CIRCUITS RCF09 (BN/WH), CCF17 (WH/OG), CCF16 (VT/GN), CCF15 (BN/YE) AND CCF14 (GN/OG) FOR A SHORT TO VOLTAGE Key in ON position. Measure the voltage between the following circuits at the 4X4 control module C281a, harness side and ground: Circuit C281a RCF09 (BN/WH) 16 CCF17 (WH/OG) 4 CCF16 (VT/GN) 3 CCF15 (BN/YE) 2 CCF14 (GN/OG) 1 Is voltage present? YES : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. NO : Go to Q26 .
  26. Q26 CHECK CIRCUITS RCF09 (BN/WH), CCF17 (WH/OG), CCF16 (VT/GN), CCF15 (BN/YE) AND CCF14 (GN/OG) FOR A SHORT TO GROUND Key in OFF position. Measure the resistance between the following circuits at 4X4 control module C281a, harness side and ground: Circuit C281a RCF09 (BN/WH) 16 CCF17 (WH/OG) 4 CCF16 (VT/GN) 3 CCF15 (BN/YE) 2 CCF14 (GN/OG) 1 Are the resistances greater than 10,000 ohms? YES : Go to Q27 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  27. Q27 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR POWER DURING ACTIVE COMMANDS Connect: 4X4 Control Module C281a Enter the following diagnostic mode on the diagnostic tool: Access Active Commands Enter the clockwise (CW) transfer case shift motor active command ON and OFF and measure the voltage between transfer case C350-15, circuit CCF07 (GN/RD) harness side and ground. Enter the counterclockwise (CCW) transfer case shift motor active command ON and OFF and measure the voltage between transfer case C350-14, circuit CCF08 (GY/OG) harness side and ground. Are the voltages 10 volts or greater while the corresponding active commands are on? YES : INSTALL a new transfer case shift motor. CLEAR the DTCs. REPEAT the self-test. NO : Go to Q28 .
  28. Q28 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR AN OPEN Measure the resistance between transfer case C350-14, circuit and 4X4 control module C281b-4, harness side, circuit CCF08 (GY/OG). Measure the resistance between transfer case C350-15, circuit and 4X4 control module C281b-5, harness side, circuit CCF07 (BN/GN). Are the resistances less than 5 ohms? YES : Go to Q29 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. Go to «Pinpoint Test V»(ref-270895-S32531385762007110700000) .
  29. Q29 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR A SHORT TO VOLTAGE Measure the voltage between 4X4 control module C281b-4, circuit CCF08 (GY/OG), harness side and ground. Measure the voltage between 4X4 control module C281b-5, circuit CCF07 (BN/GN), harness side and ground. Is voltage present? YES : Go to Q30 . NO : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test. Go to «Pinpoint Test V»(ref-270895-S32531385762007110700000) .
  30. Q30 CHECK CIRCUITS CCF08 (GY/OG) AND CCF07 (BN/GN) FOR A SHORT TO GROUND Measure the resistance between 4X4 control module C281b-5, circuit CCF07 (BN/GN) harness side and ground. Are the resistances greater than 10,000 ohms? YES : INSTALL a new 4X4 control module. REFER to «4X4 Control Module»(ref-270895-S33162709442007110700000) . Go to «Pinpoint Test V»(ref-270895-S32531385762007110700000) . NO : REPAIR the circuit. CLEAR the DTC(s). REPEAT the self-test. Go to «Pinpoint Test V»(ref-270895-S32531385762007110700000) .

The 4x4 HIGH indicator status is transmitted to the instrument cluster (IC) from the 4X4 control module through the controller area network (CAN). A steady indicator displays whether the vehicle is in 4x4 LOW or 4x4 HIGH, according to the driver selection. A 4WD system fault will cause the powertrain malfunction indicator to illuminate when a 4WD system fault condition has been detected. This light also indicates other general powertrain failures.

Possible Causes

  1. Instrument cluster (IC)
  2. 4WD system fault
  3. CAN circuits
  4. 4X4 control module

In order for the four wheel drive (4WD) system to function correctly, tires and wheels must be the same size, be in good condition and the front and rear axle ratios must match.

Possible Causes

  1. Unmatched tire sizes
  2. Unequal amounts of tire wear
  3. Unequal tire inflation pressures
  4. Unmatched front and rear axle ratios

When the vehicle is operating in 4x4 AUTO, all 4 wheels receive the same amount of torque and rotate at the same speed. The amount of traction the vehicle can achieve depends on the amount of traction each tire can establish with the road surface. In order for the 4WD system to function correctly, each tire must be in good condition and the front and rear axle ratios must match.

Possible Causes

  1. Unmatched tire sizes
  2. Unequal amounts of tire wear
  3. Unequal tire inflation pressures
  4. Unmatched front and rear axle ratios

Neutral tow is a dealer-installed option that allows the vehicle to be towed with the 4 road wheels without damaging the transmission. Neutral tow operates by disengaging the transmission from the rear differential.

Possible Causes

  1. Neutral tow indicator
  2. CAN circuits
  3. Vehicle security module (VSM)
  4. 4.0L Digital transmission range (TR) sensor
  5. 4.6L Neutral shifter position sensor
  6. Brake ON/OFF (BOO) switch
  7. Door ajar switch
  8. Ignition switch/circuitry

When the vehicle is operating in 4x4 HIGH or 4x4 LOW, (4H/4L), all 4 wheels rotate at the same speed. The amount of traction the vehicle can achieve depends on the amount of traction each tire can establish with the road surface. In order for the 4WD system to operate correctly, each wheel/tire assembly must have matching sizes and the front and rear axle ratios must match.

Possible Causes

  1. 4x4 indicators
  2. 4X4 control module
  3. Transfer case and related components
  4. Wheel/tire assemblies

More articles — Four Wheel Drive (4WD) Systems