Inspection Procedure

HINT:

Operating the engine 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 engine switch is turned off, the HDD navigation system requires approximately 6 minutes to record various types of memory and settings. As a result, after turning the engine switch off, wait 6 minutes or more before disconnecting the cable from the negative (-) battery terminal.
      • When disconnecting the cable, some systems need to be initialized after the cable is reconnected (see INITIALIZATION ).
2. CHECK FOR OPEN IN CAN BUS WIRE (AFS ECU BRANCH WIRE) 
   1. Disconnect the A37 AFS ECU connector.
      Fig 1: Identifying A37 AFS ECU Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART
      
      

      Tester Connection	Switch Condition	Specified Condition
      A37-12 (CANH) - A37-13 (CANL)	Engine switch off	54 to 69 Ω

   NG: REPAIR OR REPLACE AFS ECU BRANCH WIRE OR CONNECTOR (CANH, CANL) 

   OK: GO TO NEXT STEP 

3. CHECK HARNESS AND CONNECTOR (AFS ECU - BATTERY AND BODY GROUND) 
   1. Connect the cable to the negative (-) battery terminal.
      NOTE: When disconnecting the cable, some systems need to be initialized after the cable is reconnected (see INITIALIZATION ).
   2. Disconnect the A37 AFS ECU connectors.
      Fig 2: Identifying A37 AFS ECU Connector Terminals

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART
      
      

      Tester Connection	Condition	Specified Condition
      A37-22 (E1) - Body ground	Always	Below 1 Ω

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

      Standard voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART
      
      

      Tester Connection	Switch Condition	Specified Condition
      A37-15 (IG) - Body ground	Engine switch on (IG)	11 to 14 V
      A37-14 (IGS) - Body ground	Engine switch on (IG)	11 to 14 V

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK: REPLACE AFS ECU  (See REMOVAL )