INSPECTION PROCEDURE 2: Communication with Scan Tool MB991502 is not Possible. (Communication is not Possible with SRS.): Diagnosis

Required Special Tool: 

• MB991223 (MB991222): Harness Set (Probe)

1. STEP 1. Check that the scan tool can communicate with the other systems. 

   Q: Can the scan tool communicate with the other systems? 

   YES  : Go to Step 2.

   NO:  2.4L: Refer to SYMPTOM PROCEDURES , 3.0L: Refer to SYMPTOM PROCEDURES .

2. STEP 2. Check the communication line between the SRS-ECU and the scan tool. 
   1. Disconnect the SRS-ECU connector C-137 and the data link connector C-26, and measure at the wiring harness side.
      Fig 1: Identifying Connector C-137

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      Fig 2: Identifying Connector C-26

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      CAUTION: Do not insert a test probe into the terminal of the SRS-ECU connector C-137 from its front side directly as the connector contact pressure may be weakened.
   2. Check for continuity between the following terminals.

      C-137 connector C-26 connector

      16 - 7

      It should be less than 2 ohms.

   Q: Does continuity exist? 

   YES  : Go to Step 3.

   NO:  Go to  Step 5.

   Fig 3: Checking Continuity Between C-26 Connector Terminals

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3. STEP 3. Check the ground circuit to the SRS-ECU. 
   1. Disconnect the SRS-ECU connector C-137, and measure at the wiring harness side.
      Fig 4: Identifying Connector C-137

      Courtesy of DAIMLERCHRYSLER CORPORATION
      CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
   2. Check for continuity between terminal 3 and body ground. It should be less than 2 ohms.

   Q: Does continuity exist? 

   YES  : Go to Step 4.

   NO:  Go to  Step 6.

   Fig 5: Checking Continuity Between Terminal 3 And Body Ground

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4. STEP 4. Check the power supply circuit to the SRS-ECU. 
   1. Disconnect the negative battery terminal.
   2. Disconnect the SRS-ECU connector C-137, and measure at the wiring harness side.
   3. Connect the negative battery terminal.
   4. Turn the ignition switch to the "ON" position.
      Fig 6: Identifying Connector C-137

      Courtesy of DAIMLERCHRYSLER CORPORATION
      CAUTION: Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened.
   5. Measure the voltage between terminals 9, 12 and body ground.

      Voltage should be 9 volts or more.

   Q: Is the measured voltage within the specified range? 

   YES  : Recheck the trouble symptom. If it is not solved, replace the SRS-ECU (Refer to SRS CONTROL UNIT (SRS-ECU)  ). Then go to  Step 8.

   NO:  Go to  Step 7.

   Fig 7: Measuring Voltage Between Terminals 9, 12 And Body Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
5. STEP 5. Check the harness wires between the SRS-ECU connector C-137 (terminal No.16) and the data link connector C-26 (terminal No.7). 
   NOTE: After inspecting the intermediate connector C-140, inspect the wiring harness. If the intermediate connector C-140 is damaged, repair or replace it. Refer to , HARNESS CONNECTOR INSPECTION . Then go to  Step 8.
   Fig 8: Identifying Connector C-140

   Courtesy of DAIMLERCHRYSLER CORPORATION

   Q: Is the harness wire between the SRS-ECU connector C-137 (terminal No.16) and the data link connector C-26 (terminal No.7) in good condition? 

   YES  : Go to  step 8.

   NO:  Repair the harness wire between the SRS-ECU connector C-137 and the data link connector C-26. Then go to  Step 8.

   Fig 9: Identifying Connector C-137

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   Fig 10: Identifying Connector C-26

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6. STEP 6. Check the harness wire between the SRS-ECU connector C-137 (terminal No.3) and ground. 

   Q: Is the harness wire between the SRS-ECU connector C-137 (terminal No.3) and ground in good condition? 

   YES  : Go to  Step 8.

   NO:  Repair the harness wire between the SRS-ECU connector C-137 and ground. Then go to  Step 8.

   Fig 11: Identifying Connector C-137

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 12: Identifying Center Reinforcement

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7. STEP 7. Check the harness wires between the SRS-ECU connector C-137 (terminal No.9 and 12) and the ignition switch connector C-202 (terminal No.2). 
   NOTE: After inspecting the intermediate connectors C-308 and C-311, inspect the wiring harnesses. If the intermediate connector C-308 or C-311 is damaged, repair or replace it. Refer to , HARNESS CONNECTOR INSPECTION . Then go to Step 8.
   Fig 13: Identifying Connectors C-308, C-311

   Courtesy of DAIMLERCHRYSLER CORPORATION

   Q: Are the harness wires between the SRS-ECU connector C-137 (terminal No.9 and 12) and the ignition switch connector C-202 (terminal No.2) in good condition? 

   YES  : Go to Step 8.

   NO:  Repair the harness wires between the SRS-ECU connector C-137 and the ignition switch connector C-202. Then go to Step 8.

   Fig 14: Identifying Connector C-137

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   Fig 15: Identifying Connector C-202

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8. STEP 8. Retest the system. 

   Q: Does the scan tool communicate normally with the SRS system? 

   YES  : The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to TO COPE WITH INTERMITTENT MALFUNCTION ).

   NO:  There is no action to be taken.