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Inspection Procedure 1: The system is not turned on and off by operating the LDW switch.
 
 
caution
  • Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
COMMENTS ON TROUBLE SYMPTOM
If the system is not turned on and off by operating the LDW switch, the ETACS-ECU or the FCM/LDW/AHB-ECU may be defective.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the LDW switch
  • Malfunction of the ETACS-ECU
  • Malfunction of the FCM/LDW/AHB-ECU
  • Damaged harness wires and connectors
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Using scan tool (M.U.T.-IIISE), check data list.
Check the ETACS-ECU data list (Refer to ).
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
Connect scan tool (M.U.T.-IIISE). Refer to "How to connect Scan Tool (M.U.T.-IIISE) ."
(2) Check the LDW switch signal.
  • When the LDW switch is pressed.
 
Item No.Item nameNormal condition
109LDW switchON
Item No.Item nameNormal condition
109LDW switchON
  • When the LDW switch is not pressed.
 
Item No.Item nameNormal condition
109LDW switchOFF
Item No.Item nameNormal condition
109LDW switchOFF
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 2.
: Go to Step 4.
 
STEP 2. Using scan tool (M.U.T.-IIISE), check data list.
Check the FCM/LDW/AHB-ECU data list (Refer to ).
  • When the LDW switch is pressed.
 
Item No.Item nameNormal condition
26LDW switchON
Item No.Item nameNormal condition
26LDW switchON
  • When the LDW switch is not pressed.
 
Item No.Item nameNormal condition
26LDW switchOFF
Item No.Item nameNormal condition
26LDW switchOFF
OK: Normal condition is displayed.
Is the check result normal?
Go to Step 3.
Replace the FCM/LDW/AHB-ECU (Refer to ).
 
STEP 3. Retest the system.
Check whether system is turned on and off by operating the LDW switch.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the FCM/LDW/AHB-ECU (Refer to ).
 
STEP 4. Check of short to ground, and open circuit in LDWS line between ETACS-ECU connector and LDW switch connector.
Is the check result normal?
Go to Step 5.
Repair the connector(s) or wiring harness.
 
STEP 5. Check of open circuit in ground line between LDW switch connector and body ground.
Is the check result normal?
Go to Step 6.
Repair the connector(s) or wiring harness.
 
STEP 6. Check the LDW switch.
Check the LDW switch (Refer to ).
Is the check result normal?
Go to Step 7.
Replace the LDW switch (Refer to ).
 
STEP 7. Using scan tool (M.U.T.-IIISE), check data list.
Using the ETACS-ECU data list (Refer to ), check the LDW switch signal.
  • When the LDW switch is pressed.
 
Item No.Item nameNormal condition
109LDW switchON
Item No.Item nameNormal condition
109LDW switchON
  • When the LDW switch is not pressed.
 
Item No.Item nameNormal condition
109LDW switchOFF
Item No.Item nameNormal condition
109LDW switchOFF
OK: Normal condition is displayed.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
: Replace the ETACS-ECU (Refer to ).