Inspection Procedure

HINT:

If the transfer shift actuator cannot change from 2WD to 4WD or 4WD to 2WD or cannot lock the center differential, inspect and repair the touch select 2-4 and high-low systems first.

1. INSPECT SKID CONTROL ECU (EXI2 TERMINAL) 
   1. Disconnect the A19 ECU connector.
   2. Turn the ignition switch to ON.
   3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage 

      VOLTAGE SPECIFICATION
      
      

      Tester Connection	Condition	Specified Condition
      A19-6 (EXI2) - Body ground	4WD with center differential locked (Center differential lock detection switch ON)	Below 1.5 V
      A19-6 (EXI2) - Body ground	2WD or 4WD with center differential free (Center differential lock detection switch OFF)	10 to 14 V

   NG: Go to step 2 

   Fig 1: Identifying A19 ECU Connector Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: REPLACE VSC ACTUATOR ASSEMBLY  (See REMOVAL  )

2. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - 4WD CONTROL ECU) 
   1. Confirm that the skid control ECU connector and 4WD control ECU connector are properly connected.
   2. Disconnect the A19 and A28 ECU connectors.
   3. Inspect both the connector case and the terminal for deformation and corrosion.

      OK: No deformation or corrosion. 

   4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      RESISTANCE REFERENCE
      
      

      Tester Connection	Condition	Specified Condition
      A19-6 (EXI2) - A28-14 (4WD)	Always	Below 1 Ω
      A19-6 (EXI2) - Body ground	Always	10 kΩ or higher

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   Fig 2: Identifying A19 And A28 ECU Connector Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: Go to Next Step 

3. CHECK HARNESS AND CONNECTOR (4WD CONTROL ECU - BODY GROUND) 
   1. Confirm that the 4WD control ECU connector and shift actuator connectors are properly connected.
   2. Disconnect the A28 ECU connector.
   3. Inspect the connector case and the terminal for deformation and corrosion.

      OK: No deformation or corrosion. 

   4. Connect the A28 ECU connector.
   5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      RESISTANCE REFERENCE
      
      

      Tester Connection	Condition	Specified Condition
      A28-14 (4WD) - Body ground	4WD with center differential locked (Center differential lock detection switch ON)	Below 1 Ω
      	2WD or 4WD with center differential free (Center differential lock detection switch OFF)	10 kΩ or higher

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   Fig 3: Identifying A28 ECU Connector Terminal

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: Go to Next Step 

4. RECONFIRM DTC 
   1. Clear the DTC(s) (See DTC CHECK/CLEAR  ).
   2. Start the engine.
   3. Check if the same DTC(s) is output (See DTC CHECK/CLEAR  ).

      Result 

      RESULT REFERENCE
      
      

      Result	Proceed to
      DTC is output	A
      DTC is not output	B

   B: CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)  (See HOW TO PROCEED WITH TROUBLESHOOTING )

   A: REPLACE 4WD CONTROL ECU  (See REMOVAL )