INSPECTION PROCEDURE N-1: Theft-alarm system: Theft-alarm system is not armed (security indicator light does not illuminate).: Diagnosis

Required Special Tools: 

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

1. STEP 1. Check the ETACS-ECU power supply circuit. 

   Check that the hazard warning light illuminate when the ignition switch is in the "LOCK" (OFF) position.

   Q: Does the hazard warning light illuminate? 

   YES  : Go to Step 2.

   NO:  Check the ETACS-ECU battery circuit. Refer to INSPECTION PROCEDURE .

2. STEP 2. Check the security indicator circuit at the ETACS-ECU connector C-318. 
   1. Disconnect the ETACS-ECU connector C-318 and measure at the wiring harness side.
      Fig 1: Identifying ETACS-ECU Connector C-318

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Connect terminal 74 to the ground.

   Q: Does the security indicator light illuminate? 

   YES  : Go to  Step 8 < when using scan tool MB991502 > or 9 < when using a voltmeter >.

   NO:  Go to Step 3.

   Fig 2: Connecting Terminal 74 To Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
3. STEP 3. Check the battery power supply circuit to the combination meter. Test at combination meter connector C-101. 
   1. Disconnect the combination meter connector C-101 and measure the voltage available at the wiring harness side of the connector.
      Fig 3: Identifying Combination Meter Connector C-101

      Courtesy of DAIMLERCHRYSLER CORPORATION
   2. Measure the voltage between terminal 1 and ground.
      • The voltage should equal approximately 12 volts (battery positive voltage).

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

   YES  : Go to  Step 6.

   NO:  Go to Step 4.

   Fig 4: Measuring Voltage Between Terminal 1 And Ground

   Courtesy of DAIMLERCHRYSLER CORPORATION
4. STEP 4. Check the combination meter connector C-101 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Is combination meter connector C-101 in good condition. 

   YES  : Go to Step 5.

   NO:  Repair or replace the damaged component(s). Refer to , HARNESS CONNECTOR INSPECTION . The security indicator light should illuminate, and theft-alarm system should be armed normally.

   Fig 5: Identifying Combination Meter Connector C-101

   Courtesy of DAIMLERCHRYSLER CORPORATION
5. STEP 5. Check the wiring harness between combination meter connector C-101 (terminal 1) and battery. 
   Fig 6: Identifying Combination Meter C-101 And Joint Connectors C-141

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

   Q: Are the wiring harness between combination meter connector C-101 (terminal 1) and battery in good condition? 

   YES  : No action is necessary and testing is complete.

   NO:  Repair or replace them. The security indicator light should illuminate, and the theft-alarm system should be armed normally.

   Fig 7: Identifying Intermediate Connector C-209

   Courtesy of DAIMLERCHRYSLER CORPORATION
6. STEP 6. Check the combination meter connector C-102 and ETACS-ECU connector C-318 for loose, corroded or damaged terminals, or terminals pushed back in the connector. 

   Q: Are combination meter connector C-102 and ETACS-ECU connector C-318 in good condition? 

   YES  : Go to Step 7.

   NO:  Repair or replace the damaged component(s). Refer to HARNESS CONNECTOR INSPECTION . The security indicator light should illuminate, and the theft-alarm system should be armed normally.

   Fig 8: Locating Combination Meter Connector C-102

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 9: Locating ETACS-ECU Connector C-318

   Courtesy of DAIMLERCHRYSLER CORPORATION
7. STEP 7. Check the wiring harness between combination meter connector C-102 (terminal 47) and ETACS-ECU connector C-318 (terminal 74). 

   Q: Is the wiring harness between combination meter connector C-102 (terminal 47) and ETACS-ECU connector C-318 (terminal 74) in good condition? 

   YES  : Replace the combination meter. The security indicator light should illuminate, and the theft-alarm system should be armed normally.

   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 security indicator light should illuminate, and the theft-alarm system should be armed normally.

   Fig 10: Locating Combination Meter Connector C-102

   Courtesy of DAIMLERCHRYSLER CORPORATION
   Fig 11: Locating ETACS-ECU Connector C-318

   Courtesy of DAIMLERCHRYSLER CORPORATION
8. STEP 8. Check the input signal (by using scan tool MB991502). 

   Check the input signals from the following switches:

   • Ignition key reminder switch
   • Driver's door switch
   • Driver's and passenger's door key cylinder switch
   • Driver's and front passenger's door lock actuator switch
   • Trunk lid latch switch
   • Transmitter
   CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
   1. Connect scan tool MB991502 to the data link connector.
   2. Check that the tone alarm of scan tool MB991502 sounds when the input signal enters.

   Q: Does the tone alarm of scan tool MB991502 sound when the input signal enters? 

   YES  : Replace the ETACS-ECU. The security indicator light should illuminate, and the theft-alarm system should be armed normally.

   NO: 

   • Scan tool MB991502 does not sound when the ignition key is inserted and then removed: Refer to INSPECTION PROCEDURE  "The key reminder switch signal is not sent to the ETACS-ECU ."
     Fig 12: Connecting Scan Tool MB991502 To Data Link Connector

     Courtesy of DAIMLERCHRYSLER CORPORATION
   • Scan tool MB991502 does not sound when the driver's door is opened: Refer to INSPECTION PROCEDURE O-8 "THE DRIVER'S OR PASSENGER'S DOOR SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • Scan tool MB991502 does not sound when each of the driver's and passenger's door is unlocked by using the ignition key: Refer to INSPECTION PROCEDURE O-9 "THE DRIVER'S OR PASSENGER'S DOOR LOCK KEY CYLINDER SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • Scan tool MB991502 does not sound when each of the driver's and passenger's door is unlocked by using the inside lock knob: Refer to INSPECTION PROCEDURE O-10 "THE DRIVER'S OR PASSENGER'S DOOR LOCK ACTUATOR SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • Scan tool MB991502 does not sound when the trunk lid is opened: Refer to INSPECTION PROCEDURE O-12 "THE TRUNK LID LATCH SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • Scan tool MB991502 does not sound when the doors are locked and unlocked by using the transmitter: Refer to INSPECTION PROCEDURE O-17 "THE LOCK, UNLOCK, TRUNK OR PANIC SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  "
9. STEP 9. Check the input signal (by using scan tool voltmeter). 

   Check the input signals from the following switches:

   • Ignition key reminder switch
   • Driver's door switch
   • Driver's and passenger's door key cylinder switch
   • Driver's and front passenger's door lock actuator switch
   • Trunk lid latch switch
   • Transmitter
   1. Use special tool MB991529 to connect a voltmeter between ground terminal 4 or 5 and ETACS-ECU terminal 9 of the data link connector.
   2. Check that the voltmeter indicator deflects once when the input signal enters.

   Q: Does the voltmeter indicator deflect? 

   YES  : Replace the ETACS-ECU. The security indicator light should illuminate, and the theft-alarm system should be armed normally.

   NO: 

   • The voltmeter needle does not fluctuate when the ignition key is inserted and then removed: Refer to INSPECTION PROCEDURE O-3 "THE KEY REMINDER SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
     Fig 13: Connecting Voltmeter Between Ground Terminal 4 And 5

     Courtesy of DAIMLERCHRYSLER CORPORATION
   • The voltmeter needle does not fluctuate when the driver's door is opened: Refer to INSPECTION PROCEDURE O-8 "THE DRIVER'S OR PASSENGER'S DOOR SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • The voltmeter needle does not fluctuate when each of the driver's and passenger's door is unlocked by using the ignition key: Refer to INSPECTION PROCEDURE O-9 "THE DRIVER'S OR PASSENGER'S DOOR LOCK KEY CYLINDER SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • The voltmeter needle does not fluctuate when each of the driver's and passenger's door is unlocked by using the inside lock knob: Refer to INSPECTION PROCEDURE O-10 "THE DRIVER'S OR PASSENGER'S DOOR LOCK ACTUATOR SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • The voltmeter needle does not fluctuate when the trunk lid is opened: Refer to INSPECTION PROCEDURE O-12 "THE TRUNK LID LATCH SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."
   • The voltmeter needle does not fluctuate when the doors are locked and unlocked by using the transmitter: Refer to INSPECTION PROCEDURE O-17 "THE LOCK, UNLOCK, TRUNK OR PANIC SWITCH SIGNAL IS NOT SENT TO THE ETACS-ECU  ."