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Inspection Procedure 2: Vehicle power does not turn ON. (not possible with both of power supply mode ACC and ON)
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
When the vehicle power does not turn ON (not possible with both of power supply mode ACC and ON), the battery, CAN bus line, OSS-ECU, OSS-ECU power supply, or ground circuit may have a problem.
noteOSS-ECU can communicate with the scan tool (M.U.T.-IIISE) even when the electric motor switch is in the OFF.
 
 
TROUBLESHOOTING HINTS
  • Malfunction of 12V starter battery
  • Damaged wiring harness and connectors
  • Malfunction of electric motor switch (poor connector contact, poor electric motor switch contact)
  • Malfunction of the CAN bus line
  • Malfunction of OSS-ECU
  • ETACS-ECU malfunction
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. 12V starter battery check
Perform the 12V starter battery test to check the 12V starter battery status (Refer to GROUP 54A - 12V starter battery ).
Is the check result normal?
Go to Step 2.
Replace the 12V starter battery (Refer to GROUP 54A - 12V starter battery ).
 
STEP 2. Using scan tool (M.U.T.-IIISE), communicates with this system.
Check that the communication with scan tool (M.U.T.-IIISE) is possible.
noteIf ETACS-ECU is not active, OSS-ECU cannot communicate with the scan tool (M.U.T.-IIISE).
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the power supply mode of the electric motor switch to the OFF 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) Disconnect the negative battery terminal, and connect it again.
(3) After the negative terminal is connected, the OSS-ECU should communicate with the scan tool (M.U.T.-IIISE) within approximately 30 seconds.
(4) Turn the power supply mode of the electric motor switch to OFF.
Is the check result normal?
Go to Step 3.
Carry out the troubleshooting of "OSS-ECU power supply or ground circuit malfunction" (Refer to ).
 
STEP 3. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the power supply mode of the electric motor switch to the OFF 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) Turn the power supply mode of the electric motor switch to ON.
(3) Diagnose the CAN bus line.
(4) Turn the power supply mode of the electric motor switch to OFF.
Is the CAN bus line found to be normal?
Go to Step 4.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
 
STEP 4. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code.
Check if the diagnosis trouble code is set in the OSS-ECU.
(1)
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the power supply mode of the electric motor switch to the OFF 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) Turn the power supply mode of the electric motor switch to ON.
(3) Check if DTC is set.
(4) Turn the power supply mode of the electric motor switch to OFF.
Is the DTC set?
Refer to diagnostic trouble code chart .
Go to Step 5.
 
STEP 5. Electric motor switch check
Continuity check of electric motor switch (Refer to ).
Is the check result normal?
Go to Step 6.
Replace the electric motor switch (Refer to ).
 
STEP 6. Check of the troubles
Check that the vehicle power can be turned ON.
Is the check result normal?
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Carry out the troubleshooting relevant to the input signal of ETACS-ECU (Refer to GROUP 54A, ETACS - Diagnosis ). Then, go to Step 7.
 
STEP 7. Check of the troubles
Check that the vehicle power can be turned ON.
Is the check result normal?
This diagnosis is complete.
Replace the OSS-ECU and register the VIN (Refer to ).