OPERATION
- The battery voltage is applied to the engine control relay (terminal No. 3 and No. 4).
- The engine-A/T-ECU (terminal No. 49) makes the power transistor in the unit be in "ON" position and makes currents go on the engine control relay coil, and that makes the relay be in "ON" position.
- When the engine control relay is in "ON" position, the battery voltage is supplied to the engine-A/T-ECU, the sensor and the actuator from the engine control relay (terminal No. 1).
FUNCTION
- When the ignition switch ON signal is input to the engine-A/T-ECU, the engine-A/T-ECU places the engine control relay in the "ON" position. Accordingly, the battery voltage is supplied to the engine-A/T-ECU, sensor and actuator.
PROBABLE CAUSE
- Failed engine control relay
- Open/short circuit in engine control relay circuit or loose connector contact
- Failed engine-A/T-ECU
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Q: Is the check result normal?
YES:
Go to Step 3 
.NO: Repair.
- Remove relay, and measure at relay box side.
- Voltage between terminal No. 3 and earth, also between terminal No. 4 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 5 .NO:
- Check intermediate connector A-14, and repair if necessary. If intermediate connector is normal, check and repair harness between B-17X (terminal No. 4) engine control relay connector and battery, also between B-17X (terminal No. 3) engine control relay connector and battery.
- Check power supply line for open/short circuit.
)
)
- Measure engine-A/T-ECU terminal voltage.
- Ignition switch: ON
- Voltage between terminal No. 41 and earth, also between terminal No. 47 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Check and repair C-111 engine-A/T-ECU connector.NO: Go to Step 6
.)
)
Q: Is the check result normal?
YES:
Go to Step 7 .NO: Repair.
- Measure engine-A/T-ECU terminal voltage.
- Ignition switch: ON
- Voltage between terminal No. 98 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 12 .NO: Go to Step 8
.
Q: Is the check result normal?
YES:
Go to Step 9 .NO: Repair.
)
)
Q: Is the check result normal?
YES:
Go to Step 11 .NO: Repair.
NOTE: Before checking harness, check intermediate connectors C-106, C-202 and C-203, and repair
if necessary.
- Check output line for open/short circuit.
Q: Is the check result normal?
YES:
- Check and repair ignition switch IG1 power supply line harness and connector.
- Check power supply line for short circuit.
- Measure engine-A/T-ECU terminal voltage.
- Ignition switch: OFF
- Voltage between terminal No. 49 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 13 .NO:
- Check and repair harness between B-17X (terminal No. 2) engine control relay connector and C-110 (terminal No. 49) engine-A/T-ECU connector
- Check earthing line for open/short circuit.
- Measure engine-A/T-ECU terminal voltage.
- Ignition switch: ON
- Voltage between terminal No. 49 and earth.
OK: 1 V or less
Q: Is the check result normal?
YES:
Go to Step 17 .NO: Go to Step 14
.
Q: Is the check result normal?
YES:
Go to Step 15 .NO: Repair.
NOTE: Before checking harness, check intermediate connectors C-106, C-202 and C-203, and repair
if necessary.
- Check output line for open/short circuit.
Q: Is the check result normal?
YES:
Go to Step 16 .NO: Repair.
NOTE: Before checking harness, check intermediate connector C-17, and repair if necessary.
- Check output line for open/short circuit and damage.
Q: Is the check result normal?
YES:
Go to Step 18 .NO: Repair.
NOTE: Before checking harness, check intermediate connector A-14, and repair if necessary.
- Check power supply line for damage.
Q: Is the check result normal?
YES:
Go to Step 20 .NO: Repair.
- Check earthing line for damage.
Q: Is the check result normal?
YES:
Go to Step 16 .NO: Repair.