DIAGNOSTIC ITEM 10: Diagnose When The Scan Tool (M.U.T.-IIISE) Cannot Receive The Data Sent By Occupant Classification-ECU: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Connector check: joint connector (CAN1) and occupant classification-ECU connector 
   CAUTION: The strand end of the twist wire should be within 10 cm (3.9 inches) from the connector. For details refer to TEST EQUIPMENT  .

   When checking the joint connector, ensure that its wiring harness side and its short pins are not damaged.

   Q: Is the check result normal? 

   YES:  Go to Step  2.

   NO:  Repair the defective connector. Replace the joint connector as necessary.

2. STEP 2. Resistance measurement at joint connector (CAN1) and occupant classification-ECU connector. 
   CAUTION: A digital multimeter should be used. For details refer to TEST EQUIPMENT  .
   CAUTION: The test wiring harness should be used. For details refer to TEST EQUIPMENT  .
   1. Disconnect joint connector (CAN1) and the occupant classification-ECU connector, and measure at the wiring harness side.
   2. Turn the ignition switch to the "LOCK" (OFF) position.
      CAUTION: When measuring the resistance, disconnect the negative battery terminal. For details refer to TEST EQUIPMENT  .
   3. Ensure that the negative battery terminal is disconnected.
   4. Continuity between joint connector (CAN1) terminal No. 3 and occupant classification-ECU connector terminal No. 12

      OK: The resistance should be 2 ohms or less 

   5. Continuity between joint connector (CAN1) terminal No. 14 and occupant classification-ECU connector terminal No. 14

      OK: The resistance should be 2 ohms or less 

   CAUTION: Strictly observe the specified wiring harness repair procedure. For details refer to TEST EQUIPMENT  .

   Q: Is the check result normal? 

   YES:  <All the resistances measure 2 ohms or less> Go to Step  3.

   NO:  <Either or all of the resistances measure more than 2 ohms> Repair front seat assembly (passenger's side) connector D-518, or the wiring harness between joint connector (CAN1) and the occupant classification-ECU connector.

3. STEP 3. Resistance measurement at occupant classification-ECU connector. 
   CAUTION: A digital multimeter should be used. For details refer to TEST EQUIPMENT  .
   1. Remove the occupant classification-ECU, and measure at the equipment side.
   2. Resistance between occupant classification-ECU connector terminal Nos.12 and 14

      OK: 1 kΩ or more 

   Q: Is the check result normal? 

   YES:  Power supply to the occupant classification-ECU may be suspected. Diagnose the occupant classification-ECU. Refer to Symptom chart .

   NO:  Replace the occupant classification-ECU.