Inspection Procedure 1: Abnormality in OSS-ECU power supply and earth circuit
caution | Before replacing the ECU,
ensure that the power supply circuit, the earth circuit and the communication circuit are normal. |
COMMENTS ON TROUBLE SYMPTOM
PROBABLE CAUSES
- Damaged harness wires and connectors
- Malfunction of OSS-ECU
DIAGNOSIS PROCEDURE
STEP 1. Resistance measurement at OSS-ECU connector (PGND terminal)
(1)Disconnect the connector, and measure at the wiring harness side. |
(2)Measure the resistance between the OSS-ECU connector (PGND terminal) and body earth. OK: Continuity exists (2 Ω or less) |
Q.
Is the check result normal?
STEP 2. Check of open circuit in PGND line between OSS-ECU connector and earth joint connector
note | Before the wiring harness check, check the joint connector, and repair if necessary. |
Q.
Is the check result normal?
STEP 3. Resistance measurement at OSS-ECU connector (SGND terminal)
(1)Disconnect the connector, and measure at the wiring harness side. |
(2)Measure the resistance between the OSS-ECU connector (SGND terminal) and body earth. OK: Continuity exists (2 Ω or less) |
Q.
Is the check result normal?
STEP 4. Check of open circuit in SGND line between OSS-ECU connector and earth joint connector
Q.
Is the check result normal?
STEP 5. Voltage measurement at OSS-ECU connector (+B1 terminal)
(1)Disconnect the connector, and measure at the wiring harness side. |
(2)Check the voltage between the OSS-ECU connector (+B1 terminal) and body
earth. OK: System voltage |
Q.
Is the check result normal?
STEP 6. Check of short to power supply, short to earth, and open circuit in +B1 line between fusible link and OSS-ECU connector
note | Before the wiring harness check, check the ETACS-ECU connector and joint connector, and repair
if necessary. |
Q.
Is the check result normal?
STEP 7. Voltage measurement at OSS-ECU connector (+B2 terminal)
(1)Disconnect the connector, and measure at the wiring harness side. |
(2)Check the voltage between the OSS-ECU connector (+B2 terminal) and body
earth. OK: System voltage |
Q.
Is the check result normal?
STEP 8. Check of short to power supply, short to earth, and open circuit in +B1 line between fusible link and OSS-ECU connector
note | Before the wiring harness check, check the ETACS-ECU connector and joint connector, and repair
if necessary. |