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Center Differential Lock System: Inspection

  1. INSPECT H4 (DIFFERENTIAL LOCK "FREE") TO H4 (DIFFERENTIAL LOCK "LOCK") SHIFT 
    1. Start the engine, and make sure that the differential lock switch is in "OFF" position.
    2. Operate the transfer shift lever to "H4" position.
      Fig 1: Identifying H4 (Differential Lock "FREE") To H4 (Differential Lock "LOCK") Shift
      G05261849Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Check that the center diff. lock indicator light comes on after pressing the differential lock switch for 2 seconds. Check that the center diff. lock indicator light goes off after pressing the differential lock switch for 2 seconds.
  2. INSPECT L4 (DIFFERENTIAL LOCK "FREE") TO L4 (DIFFERENTIAL LOCK "LOCK") SHIFT 
    1. Start the engine, and make sure that the differential lock switch is in "OFF" position.
    2. Operate the transfer shift lever to "L4" position.
      Fig 2: Identifying L4 (Differential Lock "FREE") To L4 (Differential Lock "LOCK") Shift
      G05261849Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    3. Check that the center diff. lock indicator light comes on after pressing the differential lock switch for 2 seconds. Check that the center diff. lock indicator light goes off after pressing the differential lock switch for 2 seconds.
  3. INSPECT CENTER DIFFERENTIAL LOCK SWITCH 
    1. Remove the instrument panel finish lower panel sub-assembly.
    2. Remove the differential lock switch from the instrument panel finish lower sub-assembly.
    3. Inspect the continuity between the each terminal.
      TESTER CONNECTION SPECIFIED CONDITION

      Switch position Tester connection Specified condition
      OFF +B (3) - GND (4) No continuity
      Hold ON +B (3) - GND (4) Continuity
      Illumination ILL+(1) - ILL-(2) Continuity

      If continuity is not as specified, replace the differential lock switch or bulb.

  4. INSPECT ACTUATOR ASSEMBLY 
    NOTE: Inspect the actuator while overhauling the transfer or as a unit.
    1. Turn the ignition switch OFF and set the parking brake.
    2. Using a rigid rack, jack up the vehicle so that the 4 wheels do not touch on the ground.
    3. Turn the ignition switch ON and check that the front propeller shaft free or lock when switching the center differential lock.
      FRONT PROPELLER SHAFT CONDITION TABLE

      Center differential lock switch Condition of front propeller shaft
      Off (center diff. free) Possible to rotate
      On (center diff. lock) Impossible to rotate
      Fig 3: Identifying Center Differential Lock Switch
      G05261851Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      HINT

      • When the transfer gear is off the position, shift fork of the actuator could not operate.
      • When switching is impossible, jack down the vehicle to move it back and forth, and then check it again.
    4. Turn the ignition switch to ON.
    5. Check the operating sound produced by center differential lock switch operation.

      If the operating sound cannot be heard, check the four wheel drive control ECU and the wire harness in the next step. When the wire harness and four wheel drive control ECU is normal, replace the actuator.

  5. INSPECT FOUR WHEEL DRIVE CONTROL ECU 
    1. Connect the wire harness side connector to the four wheel drive control ECU and inspect wire harness side connector from the back side.
TERMINAL SPECIFIED CONDITION TABLE

Symbols (Terminal No.) Condition Specified Condition
1 (TL2) - 5 (GND)
  • Ignition switch ON
  • While switching from center diff. lock to free to Center diff. Free operation is completed
 With continuity to Without continuity
2 (TL3) - 5 (GND)
  • Ignition switch ON
  • While switching from center diff. free to lock to Center diff. Free operation is completed
 With continuity to Without continuity
3 (M2) - 4 (M1)
  • Ignition switch ON
  • Center diff. lock to Switching motor to free is in operation
 0 to 10 - 14
4 (M1) - 3 (M2)
  • Ignition switch ON
  • Center diff. lock to Switching motor to lock is in operation
 0 to 10 - 14
5 (GND) - Body ground Always Continuity
6 (C/D) - 5 (GND)
  • Ignition switch ON
  • Center differential lock switch OFF to ON
 10 - 14 to 1 or less
7 (IND) - 5 (GND)
  • Ignition switch ON
  • Indicator light is OFF to ON
 10 - 14 to 1 or less
8 (P1) - 5 (GND)
  • Ignition switch ON
  • Indicator light is OFF to ON
 10 - 14 to 1 or less
10 (IG) - 5 (GND) Ignition switch ON 10 - 14
Fig 4: Identifying Four Wheel Drive Control ECU Connector Terminals
G05261852Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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