INSPECTION PROCEDURE A-1: Scan tool MB991502 communication is not possible.: Diagnosis

Required Special Tools: 

• MB991223: Harness Set
• MB991502: Scan Tool (MUT-II)
• MB991529: Diagnostic Trouble Code Check Harness

1. STEP 1. Verify the communication with other systems. 

   Q: Can the scan tool communicate with no systems? 

   YES  : Refer to DIAGNOSIS .

   NO (can not communicate with SWS only)  : Go to Step 2.

2. STEP 2. Verify the ignition switch positions. 

   Q: Can scan tool MB991502 communicate with the ETACS-ECU with the ignition switch at any position other than "ON"? 

   YES  : Go to Step 3.

   NO:  Check the ETACS-ECU battery circuits. Refer to INSPECTION PROCEDURE P-1  .

3. STEP 3. Check the data link connector C-26 and ETACS-ECU connector C-318 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are data link connector C-26 and ETACS-ECU connector C-318 in good condition? 

   YES  : Go to Step 4.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . Scan tool MB991502 should communicate with the SWS.

   Fig 1: Identifying Data Link Connector C-26

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 2: Identifying ETACS-ECU Connector C-318

   Courtesy of DAIMLERCHRYSLER CORPORATION
4. STEP 4. Check the wiring harness between data link connector C-26 (terminal 1 and 9) and ETACS-ECU connector C-318 (terminal 67 and 51). 

   Q: Are the wiring harness between data link connector C-26 (terminal 1 and 9) and ETACS-ECU connector C-318 (terminal 67 and 51) in good condition? 

   YES  : Go to Step 5.

   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. Scan tool MB991502 should communicate with the SWS.

   Fig 3: Identifying Data Link Connector C-26

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 4: Identifying ETACS-ECU Connector C-318

   Courtesy of DAIMLERCHRYSLER CORPORATION
5. STEP 5. Check the ground circuit to the ETACS-ECU. Test at ETACS-ECU connector C-319. 
   1. Disconnect the ETACS-ECU connector C-319 and measure at the junction block side.
      Fig 5: Identifying ETACS-ECU Connector C-319

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the resistance between terminal 3 and ground.
      • The resistance should equal 2 ohms or less.

   Q: Is the measured resistance 2 ohms or less? 

   YES  : Replace the ETACS-ECU. Scan tool MB991502 should communicate with the SWS.

   NO:  Go to Step 6.

   Fig 6: Measuring Resistance Between Terminal 3 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
6. STEP 6. Check the ETACS-ECU connector C-319 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is ETACS-ECU connector C-319 in good condition? 

   YES  : Go to Step 7.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . Scan tool MB991502 should communicate with the SWS.

   Fig 7: Identifying ETACS-ECU Connector C-319

   Courtesy of DAIMLERCHRYSLER CORPORATION
7. STEP 7. Check the wiring harness between ETACS-ECU connector C-319 (terminal 3) and ground. 
   Fig 8: Identifying ETACS-ECU Connector C-319

   Courtesy of DAIMLERCHRYSLER CORPORATION
   NOTE: Also check junction block connector C-308 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-308 is damaged, repair or replace it. Refer to , HARNESS CONNECTOR INSPECTION .

   Q: Are the wiring harness between ETACS-ECU connector C-319 (terminal 3) 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. Scan tool MB991502 should communicate with the SWS.

   Fig 9: Identifying Junction Block Connector C-308

   Courtesy of DAIMLERCHRYSLER CORPORATION