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Inspection Procedure 2: Power supply circuit system
 
 
 
 
CIRCUIT OPERATION
To SRS-ECU, the power is supplied from two independent circuits (fuse No.15 and 16) via IG1 relay of ETACS-ECU.
If the power is not supplied to SRS-ECU, the communication between scan tool (M.U.T.-IIISE) and SRS-ECU cannot be established.
 
 
TROUBLESHOOTING HINTS
  • Damaged wiring harness and connectors
  • Battery failure
  • Malfunction of the charging system
  • Malfunction of SRS-ECU
 
 
DIAGNOSIS
STEP 1. Fuse Nos.15, 16 check.
Is the fuse in good condition?
Go to Step 3.
Go to Step 2.
 
STEP 2. Fuse open circuit check.
(1) Replace the fuse.
(2) Turn on the power supply mode of the electric motor switch, wait for at least one minute, and then turn off the power supply mode of the electric motor switch.
(3) Check the fuse.
Is the fuse in good condition?
Go to Step 3.
Repair the wiring harness IG1A line between the ETACS-ECU connector and the SRS-ECU connector, and replace the fuse.
 
STEP 3. Check of open circuit in GND2 line between SRS-ECU and body ground.
Is the check result normal?
Go to Step 4.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
 
STEP 4. Check of short to power supply, short to ground, and open circuit in IG1A line between SRS-ECU and ETACS-ECU.
Is the check result normal?
Go to Step 5.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
 
STEP 5. Trouble symptom check.
Is the communication between scan tool and SRS-ECU possible?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace SRS-ECU (Refer to ).