INSPECTION PROCEDURE O-3: The key reminder switch signal is not sent to the ETACS-ECU.: Diagnosis

Required Special Tools: 

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

1. STEP 1. Check the key reminder switch. 

   Disconnect key reminder switch connector C-201. Then check the continuity.

   TESTER CONNECTION SPECIFIED CONDITION CHART
   
   

   IGNITION KEY	TESTER CONNECTION	SPECIFIED CONDITION
   Removed	4 - 6	Open circuit
   Installed	4 - 6	Less than 2 ohms

   Q: Is the key reminder switch in good condition? 

   YES  : Go to Step 2.

   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. The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   Fig 1: Identifying Connector C-201

   Courtesy of DAIMLERCHRYSLER CORPORATION
2. STEP 2. Check the ground circuit to the key reminder switch. Test at key reminder switch connector C-201. 
   1. Disconnect the key reminder switch connector C-201 and measure the resistance available at the wiring harness side of the connector.
      Fig 2: Identifying Connector C-201

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the resistance between terminal 4 and ground.
      • The resistance should equal 2 ohms or less.

   Q: Is the measured resistance 2 ohms or less? 

   YES  : Go to  Step 5.

   NO:  Go to Step 3.

   Fig 3: Measuring Resistance Between Terminal 4 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
3. STEP 3. Check the key reminder switch connector C-201 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is key reminder switch connector C-201 in good condition? 

   YES  : Go to Step 4.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   Fig 4: Identifying Connector C-201

   Courtesy of DAIMLERCHRYSLER CORPORATION
4. STEP 4. Check the wiring harness between key reminder switch connector C-201 (terminal 4) and ground. 

   Q: Is the wiring harness between key reminder switch connector C-201 (terminal 4) 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. The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   Fig 5: Identifying Connector C-201 - Harness Side

   Courtesy of DAIMLERCHRYSLER CORPORATION
5. STEP 5. Check the key reminder switch connector C-201 and ETACS-ECU connector C-317 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are key reminder switch connector C-201 and ETACS-ECU connector C-317 in good condition? 

   YES  : Go to Step 6.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   Fig 6: Identifying Connector C-201 - Harness Side

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 7: Identifying Connector C-317 - Harness Side

   Courtesy of DAIMLERCHRYSLER CORPORATION
6. STEP 6. Check the wiring harness between key reminder switch connector C-201 (terminal 6) and ETACS-ECU connector C-317 (terminal 30). 

   Q: Is the wiring harness between key reminder switch connector C-201 (terminal 6) and ETACS-ECU connector C-317 (terminal 30) in good condition? 

   YES  : Go to Step 7.

   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. The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   Fig 8: Identifying Connector C-201 - Harness Side

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 9: Identifying Connector C-317 - Harness Side

   Courtesy of DAIMLERCHRYSLER CORPORATION
7. STEP 7. Check for the continuity between key reminder switch connector C-201 terminals 4 and 6. 
   1. Disconnect key reminder switch connector C-201 and measure the resistance available at the equipment side of the connector.
   2. key reminder switch connector terminal 4 and each of the other terminals < except terminal 6 > and key reminder switch connector terminal 6 and each of the other terminals < except terminal 4 >.

   Q: Does continuity exist between the terminals? 

   YES  : Replace the ETACS-ECU. The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   NO:  Replace the key reminder switch. The key reminder switch input signal should be able to be checked and the functions, which are described in the "TECHNICAL DESCRIPTION (COMMENT) ," should work normally.

   Fig 10: Identifying Connector C-201

   Courtesy of DAIMLERCHRYSLER CORPORATION