DTC 13: Front-ECU fault: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB991502: Scan Tool (MUT-II)

1. STEP 1. Verify the ignition switch position. 

   Q: Does DTC 13 set with the ignition switch at "ON" position? 

   YES  : Go to  Step 5.

   NO:  Go to Step 2.

2. STEP 2. Check the battery power supply circuit to the front-ECU. Test at front-ECU connector A-10X. 
   1. Disconnect the front-ECU connector A-10X and measure the voltage available at the relay box side of the connector.
      Fig 1: Identifying Front-ECU Connector A-10X

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the voltage between terminal 7 and ground.
      • The voltage should equal approximately 12 volts (battery positive voltage).

   Q: Is the measured voltage approximately 12 volts (battery positive voltage)? 

   YES  : Replace the front-ECU. Confirm the DTC 13 is not displayed.

   NO:  Go to Step 3.

   Fig 2: Measuring Voltage Between Terminal 7 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
3. STEP 3. Check the front-ECU connector A-10X for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is front-ECU connector A-10X in good condition? 

   YES  : Go to Step 4.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . Confirm the DTC 13 is not displayed.

   Fig 3: Identifying Front-ECU Connector A-10X

   Courtesy of DAIMLERCHRYSLER CORPORATION
4. STEP 4. Check the wiring harness between front-ECU connector A-10X (terminal 7) and battery. 

   Q: Is the wiring harness between front-ECU connector A-10X (terminal 7) and battery in good condition? 

   YES  : No action is necessary and testing is complete.

   NO:  The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Confirm the DTC 13 is not displayed.

   Fig 4: Locating Front-ECU Connector A-10X

   Courtesy of DAIMLERCHRYSLER CORPORATION
5. STEP 5. Check the ground circuit to the front-ECU. Test at front-ECU connector A-11X. 
   1. Disconnect the front-ECU connector A-11X and measure the resistance available at the relay box side of the connector.
      Fig 5: Locating Front-ECU Connector A-11X

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the resistance between terminal 31 and ground.
      • The resistance should equal 2 ohms or less.

   Q: Is the measured resistance 2 ohms or less? 

   YES  : Go to  Step 8.

   NO:  Go to Step 6.

   Fig 6: Measuring Resistance Between Terminal 31 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
6. STEP 6. Check the front-ECU connector A-11X for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is front-ECU connector A-11X in good condition? 

   YES  : Go to Step 7.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . Confirm the DTC 13 is not displayed.

   Fig 7: Locating Front-ECU Connector A-11X

   Courtesy of DAIMLERCHRYSLER CORPORATION
7. STEP 7. Check the wiring harness between front-ECU connector A-11X (terminal 31) and ground. 

   Q: Is the wiring harness between front-ECU connector A-11X (terminal 31) and ground in good condition? 

   YES  : No action is necessary and testing is complete.

   NO:  The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Confirm the DTC 13 is not displayed.

   Fig 8: Locating Front-ECU Connector A-11X

   Courtesy of DAIMLERCHRYSLER CORPORATION
8. STEP 8. Check the front-ECU connector A-11X and ETACS-ECU connector C-318 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are front-ECU connector A-11X and ETACS-ECU connector C-318 in good condition? 

   YES  : Go to Step 9.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . Confirm the DTC 13 is not displayed.

   Fig 9: Locating Front-ECU Connector A-11X

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 10: Identifying ETACS-ECU Connector C-318

   Courtesy of DAIMLERCHRYSLER CORPORATION
9. STEP 9. Check the wiring harness between front-ECU connector A-11X (terminal 22) and ETACS-ECU (terminal 59) connector C-318. 
   Fig 11: Identifying Front-ECU Connector A-11X

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 12: Identifying ETACS-ECU Connector C-318

   Courtesy of DAIMLERCHRYSLER CORPORATION
   NOTE: Also check intermediate connector C-209 and joint connector C-141 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-209 and joint connector C-141 are damaged, repair or replace the damaged component(s) as described in , HARNESS CONNECTOR INSPECTION .

   Q: Are the wiring harness between front-ECU connector A-11X (terminal 22) and ETACS-ECU connector C-318 (terminal 59) in good condition? 

   YES  : Go to Step 10.

   NO:  The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Confirm the DTC 13 is not displayed.

   Fig 13: Identifying Joint Connector C-141

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 14: Identifying Intermediate Connector C-209

   Courtesy of DAIMLERCHRYSLER CORPORATION
10. STEP 10. Replacement of ECU. 
    1. Replace the front-ECU.
    2. Confirm the DTC 13 is not displayed.

    Q: Does DTC 13 set? 

    YES  : Replace the ETACS-ECU. Confirm the DTC 13 is not displayed.

    NO:  No action is necessary and testing is complete.