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Center Diff. Lock System: Inspection: Notes

  1. INSPECT H4 (Differential lock "FREE") <=> 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.
    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.

      Fig 1: Operating Transfer Shift Lever To "H4" Position
      G02963187Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. INSPECT L4 (Differential lock "FREE") <=> 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.
    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.

      Fig 2: Operating Transfer Shift Lever To "H4" Position
      G02963188Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. INSPECT CENTER DIFFERENTIAL LOCK SWITCH CONTINUITY 
    1. Remove the instrument panel finish lower panel sub-assy.
    2. Remove the differential lock switch from the instrument panel finish lower sub-assy.
    3. Inspect the continuity between the each terminal.
      TESTER CONNECTION AND 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.

      Fig 3: Identifying Center Differential Lock Switch Connector Terminals
      G02963189Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. INSPECT ACTUATOR 
    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.
      CENTER DIFFERENTIAL LOCK SWITCH POSITION

      Center differential lock switch Condition of front propeller shaft
      Off (center def. free) Possible to rotate
      On (center def. lock) Impossible to rotate

      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, as shown.
      Fig 4: Identifying Four Wheel Drive Control ECU Connector Terminals
      G02963190Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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