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Inspection Procedure 3: Abnormality in KOS&OSS-ECU power supply and ground circuits
 
 
cautionBefore replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
When the KOS does not work at all or the KOS&OSS-ECU cannot communicate with the scan tool, the KOS&OSS-ECU power supply or the ground circuit may be defective.
 
 
TROUBLESHOOTING HINTS
  • Damaged wiring harness and connectors
  • Malfunction of KOS&OSS-ECU
 
 
DIAGNOSIS
STEP 1. Resistance measurement at KOS&OSS-ECU connector (PGND, SGND terminal)
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Measure the resistance between the KOS&OSS-ECU connector (PGND, SGND terminal) and body ground.
OK: Continuity exists (2 ohms or less)
Is the check result normal?
Go to Step 3.
Go to Step 2.
 
STEP 2. Check of open circuit in PGND, SGND line between KOS&OSS-ECU connector and body ground
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 ).
Repair the connector(s) or wiring harness.
 
STEP 3. Voltage measurement at KOS&OSS-ECU connector (+B, IOD terminal)
(1) Disconnect the connector, and measure at the wiring harness side.
(2) Check the voltage between the KOS&OSS-ECU connector (+B, IOD terminal) and body ground.
OK: System voltage
Is the check result normal?
Replace the KOS&OSS-ECU and register the chassis number (Refer to ).
Go to Step 4.
 
STEP 4. Check of short to power supply, short to ground, and open circuit in +B, IOD line between fusible link and KOS&OSS-ECU connector
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 ).
Repair the connector(s) or wiring harness.