Diagnostic Item 20: Diagnose When The Scan Tool (M.U.T.-IIISE) Cannot Receive The Data Sent By ECM: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB992006: Extra Fine Probe

1. STEP 1. Connector check: joint connector (CAN4) and engine control module 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 (CAN4) and engine control module 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 the joint connector (CAN4) and the ECM 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 (CAN4) terminal No. 10 and ECM connector terminal No. 151

      OK: The resistance should be 2 ohms or less 

   5. Continuity between joint connector (CAN4) terminal No. 21 and ECM connector terminal No. 152

      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 the wiring harness between joint connector (CAN4) and the ECM.

3. STEP 3. Resistance measurement at ECM connector. 
   CAUTION: A digital multimeter should be used. For details Refer to TEST EQUIPMENT .
   1. Remove the ECM, and measure at the equipment side.
   2. Resistance between ECM connector terminal Nos.151 and 152

      OK: 120 ± 20 ohms 

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

   Q: Is the check result normal? 

   YES  : <Within 120 ± 20 ohms> Power supply to the engine control module may be suspected. Diagnose the fuel system. Refer to SYMPTOM PROCEDURE - POWER SUPPLY SYSTEM AND IGNITION SWITCH-IG SYSTEM .

   NO  : <Not within 120 ± 20 ohms> Replace the engine control module.