Inspection Procedure N-1
Theft-alarm System: Theft-alarm System is not Armed (Theft-alarm Indicator Light does not Illuminate).NOTE: This troubleshooting requires use of scan tool MB991958 and SWS monitor kit MB991862. For details of how to use the SWS monitor, refer to "How to use SWS monitor." How To Use SWS Monitor
Theft-alarm Indicator Light Circuit Part 1:
Theft-alarm Indicator Light Circuit Part 2:
CIRCUIT OPERATION
- When the ETACS-ECU receives a "LOCK" signal from the door lock actuator switch, it illuminates the security indicator light for approximately 18 seconds, and then set the theft-alarm system.
- The ETACS-ECU sets the theft-alarm system according to the input signals from the following signals:
- Ignition key reminder switch: ON
- Driver's and front passenger's door switch: OFF
- Driver's and front passenger's door lock key cylinder switch: OFF
- Driver's and front passenger's doors actuator switch: LOCK
- Liftgate latch switch: OFF
- Liftgate lock key cylinder switch: OFF
- Trunk lid latch switch: OFF
- Trunk lid lock key cylinder switch: OFF
- Hood switch: OFF
- Transmitter switch: LOCK
- Vehicle condition:
- Ignition key: Removed from the ignition key cylinder
- All doors: Closed
- Driver's and front passenger's door lock key cylinder: Not being operated
- Liftgate: Opened
- Liftgate lock key cylinder: Not operating
- Trunk lid: Closed
- Trunk lid lock key cylinder: Not operating
- Hood: Closed
- Transmitter: Turn to the "LOCK" position
TECHNICAL DESCRIPTION (COMMENT)
If the theft-alarm system is set normally, the input signal circuit, the "SECURITY" indicator light or the ETACS-ECU may be defective.
TROUBLESHOOTING HINTS
- Malfunction of the theft-alarm indicator light
- Malfunction of the ignition key reminder switch
- Malfunction of the driver's or front passenger's door switch
- Malfunction of the driver's or front passenger's door lock key cylinder switch
- Malfunction of the driver's and front passenger's door lock actuator switch
- Malfunction of the liftgate latch switch
- Malfunction of the liftgate lock key cylinder switch signal
- Malfunction of the trunk lid latch switch
- Malfunction of the trunk lid lock key cylinder switch signal
- Malfunction of the hood switch
- Malfunction of the transmitter
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface
- MB991827: MUT-III USB cable
- MB991911: MUT-III Main harness B
- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991922: Probe harness
STEP 1. Use scan tool MB991958 to select "ECU COMM Check" on the SWS monitor display.
Check the ETACS-ECU.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. Connect special tool MB991911 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991824.
1. Connect the special tool. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Turn the ignition switch to the "LOCK" (OFF) position.
3. Operate scan tool MB991958 according to the procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."
4. Scan tool MB991958 should show "OK" on the "ECU COMM Check" menus for both the "ETACS ECU" menus.
Q: Is "OK" displayed on the "ETACS ECU" menu?
YES: Go to Step 2.
NO: Refer to Inspection Procedure A-3 "Communication with ETACS-ECU is impossible."
STEP 2. Check at ETACS-ECU connector C-118 in order to check the theft-alarm indicator light circuit.
1. Disconnect ETACS-ECU connector C-118, and measure at the wiring harness side.
2. The theft-alarm indicator light should illuminate when terminal 74 is grounded.
Q: Does the theft-alarm indicator light illuminate?
YES: Go to Step 10.
NO: Go to Step 3.
STEP 3. Check the theft-alarm indicator light.
Q: Is the theft-alarm indicator light bulb in good condition?
YES: Go to Step 4.
NO: Replace the bulb. The theft-alarm indicator light should illuminate, and the theft-alarm system should be set normally.
STEP 4. Check the combination meter (printed-circuit board).
1. Remove the combination meter.
2. Remove the theft-alarm indicator light bulb. Then measure the resistance value between the bulb terminals.
3. Install the bulb to the combination meter, and then measure the resistance value between connector C-42 terminals 31 and 32. The measured resistance value should be roughly the same as the value measured in Step (2).
Q: Are these two resistance values extremely different?
YES: Repair or replace the combination meter (printed circuit board). Check that the seat belt warning light illuminates normally.
NO (much the same): Go to Step 5.
STEP 5. Check at combination meter connector C-42 in order to check the battery power supply line to the theft-alarm indicator light circuit.
1. Disconnect combination meter connector C-42, and check at the wiring harness side.
2. Measure the voltage between terminal 32 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).
Q: Does the measured voltage correspond with this range?
YES: Go to Step 8.
NO: Go to Step 6.
STEP 6. Check combination meter connector C-42 for damage.
Q: Is combination meter connector C-42 in good condition?
YES: Go to Step 7.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The theft-alarm indicator light should illuminate, and the theft-alarm system should be set normally.
STEP 7. Check the wiring harness between combination meter connector C-42 (terminal 32) and the battery.
NOTE: Also check joint connector C-78 and intermediate connector C-89. If joint connector C-78 or intermediate connectors C-89 is damaged, repair or replace the connector as described in Harness Connector Inspection.
Q: Is the wiring harness between combination meter connector C-42 (terminal 32) and the battery in good condition?
YES: No action to be taken.
NO: Repair the wiring harness. The theft-alarm indicator light should illuminate, and the theft-alarm system should be set normally.
STEP 8. Check combination meter connector C-42 and ETACS-ECU connector C-118 for damage.
Q: Are combination meter connector C-42 and ETACS-ECU connector C-118 in good condition?
YES: Go to Step 9.
NO: Repair or replace the connector. Refer to Harness Connector Inspection. The theft-alarm indicator light should illuminate, and the theft-alarm system should be set normally.
STEP 9. Check the wiring harness between combination meter connector C-42 (terminal 31) and ETACS-ECU connector C-118 (terminal 74).
Q: Is the wiring harness between combination meter connector C-42 (terminal 31) and ETACS-ECU connector C-118 (terminal 74) in good condition?
YES: No action to be taken.
NO: Repair the wiring harness. The theft-alarm indicator light should illuminate, and the theft-alarm system should be set normally.
STEP 10. Check the input signal by using "DATA LIST" of the SWS monitor.
Satisfy the following conditions to check the driver's and front passenger's door switches.
- Driver's door: Open (driver's door switch is on)
However, the door should be closed when checking the front passenger's door switch.
- Front passenger's door: Open (front passenger's door switch is on)
However, the door should be closed when checking the driver's door switch.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. Also connect SWS monitor kit MB991862 after turning on scan tool MB991958.
1. Connect the special tool. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Operate scan tool MB991958 according to the procedure below to display "ETACS ECU."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Data List."
f. Select "ETACS ECU."
3. The scan tool should show the given values when each switch is operated.
NOTE: The scan tool display changes when the driver's or the front passenger's door is opened. If any of the doors is open, the system can not be checked correctly.
Q: The scan tool shows the respective normal condition for item "FRONT DOOR SW."
YES: Go to Step 11.
NO: Refer to Inspection Procedure O-6 "ETACS-ECU does not receive a signal from the driver's or front passenger's door switch."
STEP 11. Check the input signal (by using the Pulse check mode of the monitor).
Check the input signals from the following switches:
- Key reminder switch
- Driver's and front passenger's door lock actuator switch
- Driver's and front passenger's door lock key cylinder switch
- Hood switch
- Liftgate latch switch
- Liftgate lock key cylinder switch
- Trunk lid latch switch
- Trunk lid lock key cylinder switch
1. Operate scan tool MB991958 according to the procedure below to display "Pulse check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "Pulse Checking."
2. Check if scan tool MB991958 sounds or not.
Q: When the key reminder switch, driver's and front passenger's door lock actuator switches, driver's and front passenger's door look key cylinder switches, hood switch, liftgate latch switch
Normal conditions are displayed for all the items: Replace the ETACS-ECU. The theft-alarm indicator light should illuminate, and the theft-alarm system should be set normally.
Scan tool MB991958 does not sound when the key reminder switch is operated: Refer to Inspection Procedure P-1 "ETACS-ECU does not receive a signal from the key reminder switch."
Scan tool MB991958 does not sound when the driver's and the front passenger's door lock actuator switches are operated: Refer to Inspection Procedure P-5 "ETACS-ECU does not receive signals from the driver's or the front passenger's door lock actuator switch."
Scan tool MB991958 does not sound when the driver's and the front passenger's door lock actuator switches are operated: Refer to Inspection Procedure P-4 "ETACS-ECU does not receive signals from the driver's or the front passenger's door lock key cylinder switch."
Scan tool MB991958 does not sound when the hood switch is operated: Refer to Inspection Procedure P-8 "ETACS-ECU does not receive a signal from the hood switch."
When the liftgate latch switch
When the liftgate lock key cylinder switch