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INSPECTION PROCEDURE A-6: Ignition "LOCK (OFF)" Position-linked Door Unlock Function does not Operate.
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If a door is not unlocked when the ignition switch is turned to the LOCK position, a malfunction of the CAN bus line, ignition switch or ETACS-ECU is suspected. Also, the ignition "LOCK" position-linked door unlock function may have been set to "Disabled" with the customization function.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of CAN bus line
  • Malfunction of ETACS-ECU
  • Malfunction of ignition switch
  • Damaged wiring harness and connectors
 
 
DIAGNOSIS
STEP 1. Checking central door unlocking operation
Check that the central door locking system works normally.
Is the check result normal?
Go to Step 2.
Refer to trouble symptom chart .
 
STEP 2. Check the customization function.
Check that the following other than "Disabled" is set for "Auto door unlock by ignition LOCK position" with the customization function.
  • Always (LOCK pos)
Is the check result normal?
Go to Step 3.
Set the function "Always (LOCK pos)" for "Auto door unlock by ignition LOCK position" with the customization function (Refer to ).
 
STEP 3. Using scan tool MB991958, check CAN bus for diagnostic trouble code.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to GROUP 42B, "How to connect scan tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Check whether CAN bus lines related DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Repair the CAN bus line (Refer to GROUP 54C, CAN bus diagnostics table ).
Go to Step 4.
 
STEP 4. Using scan tool MB991958, read the diagnostic trouble code.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to GROUP 42B, "How to connect scan tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Check whether any DTC is set to ETACS-ECU.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Diagnose the ETACS-ECU. Refer to GROUP 54A, Diagnostic trouble code chart .
Go to Step 5.
 
STEP 5. Using scan tool MB991958, check data list.
Check the signal related to the central door locking system.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to GROUP 42B, "How to connect scan tool (M.U.T.-III) ."
(2) Turn the ignition switch to the "ON" position.
(3) Check whether the ETACS-ECU related DTC is set.
  • Turn the ignition switch to the "LOCK" (OFF) position.
 
Item No.Item nameNormal condition
Item 254IG voltageBattery positive voltage
(4) Turn the ignition switch to the "LOCK" (OFF) position.
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 6.
Refer to GROUP 54A - Inspection Procedure 2 "Defective power supply system of the ignition switch"
 
STEP 6. Retest the system.
Check that turning the ignition switch to the "LOCK" position unlocks the doors.
Is the check result normal?
No action is necessary and testing is complete.
Replace the ETACS-ECU.