Inspection Procedure 19: Engine-ECU Power Supply, Engine Control Relay, Ignition Switch-IG1 System
OPERATION
- Battery voltage is applied to the engine control relay power supply line.
- Engine-ECU connector terminal C/R applies current to the engine control relay coil by turning ON the power transistor in the unit in order to turn the relay ON.
- When the engine control relay is turned ON, the battery power will be supplied from the engine control relay connector terminal to the engine-ECU, sensor and actuator.
FUNCTION
- When the ignition switch ON signal is input into the engine-ECU via ETACS-ECU, the engine-ECU turns ON the engine control relay. This causes battery voltage to be supplied to the engine-ECU, sensor and actuator.
PROBABLE CAUSES
- Failed battery
- Failed engine control relay
- Failed OSS-ECU
- Open/short circuit or damage in the engine control relay circuit or loose connector contact.
- Open/short circuit or damage in the engine control relay circuit or loose connector contact.
- Open circuit or damage in the engine-ECU earth circuit or loose connector contact.
- Failed ETACS-ECU
- Failed engine-ECU
|
- Battery check (Refer to GROUP 54A - Battery - On-vehicle Service - Battery Test
).
|
|
Q.
Is the check result normal?
|
|
Go to Step 2.
|
|
|
|
Replace the battery.
|
|
|
|
STEP 2. Check engine control relay itself.
|
|
- Check engine control relay itself (Refer to
).
|
|
Q.
Is the check result normal?
|
|
Go to Step 3.
|
|
|
|
Replace the engine control relay.
|
|
|
|
STEP 3. Voltage measurement at engine control relay connector (power supply line).
|
|
(1)Remove the relay, and measure at the relay box side.
|
|
(2)Check the voltage between the engine control relay connector (power supply line) and body earth. OK: System voltage
|
|
Q.
Is the check result normal?
|
|
Go to Step 4.
|
|
|
|
![](../../../buttons/03btn002.png)
Repair or replace the connector(s), or check and repair the harness of short to earth, and open circuit in power supply line between battery and engine control relay connector.
|
|
|
|
STEP 4. Voltage measurement at engine-ECU connector (C/R terminal).
|
|
(1)Disconnect the connector, and measure at the wiring harness side.
|
|
(2)Check the voltage between the engine-ECU connector (C/R terminal) and body earth. OK: System voltage
|
|
Q.
Is the check result normal?
|
|
Go to Step 5.
|
|
|
|
![](../../../buttons/03btn002.png)
Repair or replace the connector(s), or check and repair the harness of short to earth, and open circuit in C/R line between engine control relay connector and engine-ECU connector.
|
|
|
|
STEP 5. Voltage measurement at engine-ECU connector (BAT1 terminal).
|
|
(1)Disconnect the connector, and measure at the wiring harness side.
|
|
(2)Short-circuit engine-ECU connector (C/R terminal) to the body earth.
|
|
(3)Check the voltage between the engine-ECU connector (BAT1 terminal) and body earth. OK: System voltage
|
|
Q.
Is the check result normal?
|
|
Go to Step 8.
|
|
|
|
Go to Step 6.
|
|
|
|
STEP 6. Check of short to earth, and open circuit in BAT1 line between engine control relay connector and engine-ECU connector.
|
|
Q.
Is the check result normal?
|
|
Go to Step 7.
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
STEP 7. Check of harness damage in power supply line between the battery and engine control relay connector.
|
|
Q.
Is the check result normal?
|
|
![](../../../buttons/03btn001.png)
Repair or replace the connector(s), or check and repair the harness of damage in C/R line between engine control relay connector and engine-ECU connector.
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
STEP 8. Check of damage in BAT1 line between engine-ECU connector and engine control relay connector.
|
|
Q.
Is the check result normal?
|
|
Go to Step 9.
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
STEP 9. Check of harness damage in power supply line between battery and engine control relay connector.
|
|
Q.
Is the check result normal?
|
|
Go to Step 10.
|
|
|
|
Repair the connector(s) or wiring.
|
|
|
|
STEP 10. Voltage measurement at engine-ECU connector (IGN terminal).
|
|
(1)Disconnect the connector, and measure at the wiring harness side.
|
|
(3)Check the voltage between the engine-ECU connector (IGN terminal) and body earth. OK: System voltage
|
|
Q.
Is the check result normal?
|
|
Go to Step 14.
|
|
|
|
Go to Step 11.
|
|
|
|
STEP 11. Voltage measurement at ETACS-ECU connector (IG1 terminal).
|
|
(1)Disconnect the connector, and measure at the wiring harness side.
|
|
(3)Check the voltage between the ETACS-ECU connector (IG1 terminal) and body earth. OK: System voltage
|
|
Q.
Is the check result normal?
|
|
Go to Step 13.
|
|
|
|
NO : Go to Step 12.
|
|
|
|
STEP 12. Check of short to earth, and open circuit in IG1 line between OSS-ECU connector and ETACS-ECU connector.
|
|
Q.
Is the check result normal?
|
|
Perform troubleshooting of OSS System (Refer to GROUP 42B - Troubleshooting - Trouble Symptom Chart ).
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
STEP 13. Continuity check on ETACS-ECU connectors
|
|
(1)Disconnect the connector, and measure at the ETACS-ECU side.
|
|
(2)Continuity check between the ETACS-ECU connector (IG1 terminal) and the ETACS-ECU connector (IGN terminal).
note |
Connect the (+) side of circuit tester to terminal IGN.
|
OK: Continuity
|
|
Q.
Is the check result normal?
|
|
![](../../../buttons/03btn001.png)
Repair or replace the connector(s), or check and repair the harness of damage in IGN line between ETACS-ECU connector and engine-ECU connector.
|
|
|
|
Replace the ETACS-ECU.
|
|
|
|
STEP 14. Check of harness damage in IGN line between ETACS-ECU connector and engine-ECU connector.
|
|
Q.
Is the check result normal?
|
|
Go to Step 15.
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
STEP 15. Continuity check on ETACS-ECU connectors
|
|
(1)Disconnect the connector, and measure at the ETACS-ECU side.
|
|
(2)Continuity check between the ETACS-ECU connector (IG1 terminal) and the ETACS-ECU connector (IGN terminal).
note |
Connect the (+) side of circuit tester to terminal IGN.
|
OK: Continuity
|
|
Q.
Is the check result normal?
|
|
Go to Step 16.
|
|
|
|
Replace the ETACS-ECU.
|
|
|
|
STEP 16. Check of harness damage in IG1 line between OSS-ECU connector and ETACS-ECU connector.
|
|
Q.
Is the check result normal?
|
|
Go to Step 17.
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|
|
STEP 17. Check of open circuit and damage in GNDB, GNDE line between engine-ECU connector and body earth.
|
|
Q.
Is the check result normal?
|
|
Replace the engine-ECU.
|
|
|
|
Repair the connector(s) or wiring harness.
|
|
|