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Inspection Procedure 1: The FCM cannot be turned on or off when the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is operated.
 
 
caution
  • Whenever ECU is replaced, ensure that the CAN bus lines are normal.
 
 
COMMENTS ON TROUBLE SYMPTOM
If the system is not turned on and off by operating the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch, the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch, the ASC-ECU or the FCM/LDW/AHB-ECU may be defective.
noteThe ultrasonic misacceleration mitigation system will also not operate normally unless the signal of forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is normally input.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch
  • Malfunction of the ASC-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 ASC-ECU data list (Refer to GROUP 35C - Troubleshooting ).
(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 input signals from the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch.
  • When the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is pressed.
 
Item No.Item nameNormal condition
66FCM ON/OFF switchON
Item No.Item nameNormal condition
66FCM ON/OFF switchON
  • When the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is not pressed.
 
Item No.Item nameNormal condition
66FCM ON/OFF switchOFF
Item No.Item nameNormal condition
66FCM ON/OFF 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 forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is pressed.
 
Item No.Item nameNormal condition
25FCM ON/OFF switchON
Item No.Item nameNormal condition
25FCM ON/OFF switchON
  • When the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is not pressed.
 
Item No.Item nameNormal condition
25FCM ON/OFF switchOFF
Item No.Item nameNormal condition
25FCM ON/OFF 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 forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF 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 FCSW line between ASC-ECU connector and forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF 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 forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF 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 forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch.
Refer to .
Is the check result normal?
Go to Step 7.
Replace the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch (Refer to ).
 
STEP 7. Using scan tool (M.U.T.-IIISE), check data list.
Check the ASC-ECU data list (Refer to GROUP 35C - Troubleshooting ).
  • When the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is pressed.
 
Item No.Item nameNormal condition
66FCM ON/OFF switchON
Item No.Item nameNormal condition
66FCM ON/OFF switchON
  • When the forward collision mitigation system (FCM) and ultrasonic misacceleration mitigation system ON/OFF switch is not pressed.
 
Item No.Item nameNormal condition
66FCM ON/OFF switchOFF
Item No.Item nameNormal condition
66FCM ON/OFF 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 ASC-ECU (Refer to GROUP 35C - ASC-ECU ).