Inspection Procedure

HINT:

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL 
   1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
      CAUTION: Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation.
      NOTE: After the ignition switch is turned OFF, the navigation system requires approximately 90 seconds to record various types of memory and settings. As a result, after turning the ignition switch OFF, wait 90 seconds or more before disconnecting the cable from the negative (-) battery terminal.
2. CHECK FOR OPEN IN CAN BUS WIRE (4WD CONTROL ECU BRANCH WIRE) 
   1. Disconnect the A25 4WD control ECU connector.
   2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION TABLE
      
      

      Tester Connection	Switch Condition	Specified Condition
      A25-19 (CANH) - A25-20 (CANL)	Ignition switch OFF	54 to 69 Ω

      Fig 1: Identifying A25 4WD Control ECU Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   NG: REPAIR OR REPLACE 4WD CONTROL ECU BRANCH WIRE OR CONNECTOR (CANH, CANL) 

   OK: Go to Next Step 

3. CHECK HARNESS AND CONNECTOR (4WD CONTROL ECU - BATTERY AND BODY GROUND) 
   1. Reconnect the cable to the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
   2. Disconnect the A26 4WD control ECU connector.
   3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION TABLE
      
      

      Tester Connection	Condition	Specified Condition
      A26-4 (GND) - Body ground	Always	Below 1 Ω

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

      Standard voltage 

      STANDARD VOLTAGE SPECIFICATION TABLE
      
      

      Tester Connection	Switch Condition	Specified Condition
      A26-3 (IG) - Body ground	Ignition switch ON	11 to 14 V

      Fig 2: Identifying A26 4WD Control ECU Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK: REPLACE 4WD CONTROL ECU  (See REMOVAL )