Inspection Procedure 23: Engine-A/T-ECU Power Supply, Engine Control Relay, Ignition Switch-IG1 System

OPERATION

The battery voltage is applied to the engine control relay (terminal No. 3 and 4).

The engine-A/T-ECU (terminal No. 57) 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 (terminal No. 34 and No. 43), 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

DIAGNOSIS PROCEDURE

STEP 1. Check battery voltage.

Measure battery voltage during cranking.

OK: 8 V or more

Q: Is the check result normal?

YES: Go to Step 2

.
NO: Check battery (Refer to GROUP 54A - Battery - On-vehicle Service - Battery test

STEP 2. Connector check: B-17X engine control relay connector

Q: Is the check result normal?

YES: Go to Step 3

.
NO: Repair.

STEP 3. Check engine control relay.

Check engine control relay (Refer to ).

Q: Is the check result normal?

YES: Go to Step 4

.
NO: Replace engine control relay.

STEP 4. Perform voltage measurement at B-17X engine control relay connector.

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. 3 and terminal No. 4) engine control relay connector and battery.

Check power supply line for open/short circuit.

STEP 5. Perform voltage measurement at C-135 engine-A/T-ECU connector.

Measure engine-A/T-ECU terminal voltage.

Ignition switch: ON

Voltage between terminal No. 34 and earth, also between terminal No. 43 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Check and repair C-135 engine-A/T-ECU connector.
NO: Go to Step 6

STEP 6. Connector check: C-135 engine-A/T-ECU connector

Q: Is the check result normal?

YES: Go to Step 7

.
NO: Repair.

STEP 7. Perform voltage measurement at C-135 engine-A/T-ECU connector.

Measure engine-A/T-ECU terminal voltage.

Ignition switch: ON

Voltage between terminal No. 50 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Go to Step 10

.
NO: Go to Step 8

STEP 8. Connector check: C-303 ignition switch connector

Q: Is the check result normal?

YES: Go to Step 9

.
NO: Repair.

STEP 9. Check ignition switch.

Check ignition switch (Refer to GROUP 54A - Ignition Switch - Ignition Switch - Inspection ).

Q: Is the check result normal?

YES:

Check intermediate connector C-106, C-202 and C-203, and repair if necessary. If intermediate connector is normal, check and repair harness between C-303 (terminal No. 2) ignition switch connector and C-135 (terminal No. 50) engine-A/T-ECU connector.

Check output line for open/short circuit and damage.

NO: Replace ignition switch.

STEP 10. Perform voltage measurement at C-135 engine-A/T-ECU connector.

Measure engine-A/T-ECU terminal voltage.

Ignition switch: OFF

Voltage between terminal No. 57 and earth.

OK: System voltage

Q: Is the check result normal?

YES: Go to Step 11

.
NO:

Check and repair harness between B-17X (terminal No. 2) engine control relay connector and C-135 (terminal No. 57) engine-A/T-ECU connector.

Check earthing line for open/short circuit.

STEP 11. Check harness between B-17X (terminal No. 3 and No. 4) engine control relay connector and battery.

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 12

.
NO: Repair.

STEP 12. Check harness between C-303 (terminal No. 2) ignition switch connector and C-135 (terminal No. 50) engine-A/T-ECU connector.

NOTE: Before checking harness, check intermediate connectors C-106, C-202 and C-203 and repair if necessary.

Check output line for damage.

Q: Is the check result normal?

YES: Go to Step 13

.
NO: Repair.

STEP 13. Check harness between C-135 (terminal No. 33 and No. 42) engine-A/T-ECU connector and body earth.

Check earthing line for damage.

Q: Is the check result normal?

YES: Replace engine-A/T-ECU
NO: Repair.


Inspection Procedure 23: Engine-A/T-ECU Power Supply, Engine Control Relay, Ignition Switch-IG1 System

OPERATION The battery voltage is applied to the engine control relay (terminal No. 3 and 4). The engine-A/T-ECU (terminal No. 57) 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 (terminal No. 34 and No. 43), 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
	DIAGNOSIS PROCEDURE

	STEP 1. Check battery voltage. Measure battery voltage during cranking. OK: 8 V or more Q: Is the check result normal? YES: Go to Step 2 . NO: Check battery (Refer to GROUP 54A - Battery - On-vehicle Service - Battery test ).
	STEP 2. Connector check: B-17X engine control relay connector
	Q: Is the check result normal? YES: Go to Step 3 . NO: Repair.
	STEP 3. Check engine control relay. Check engine control relay (Refer to ). Q: Is the check result normal? YES: Go to Step 4 . NO: Replace engine control relay.
	STEP 4. Perform voltage measurement at B-17X engine control relay connector.
	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. 3 and terminal No. 4) engine control relay connector and battery. Check power supply line for open/short circuit.
	STEP 5. Perform voltage measurement at C-135 engine-A/T-ECU connector.
	Measure engine-A/T-ECU terminal voltage. Ignition switch: ON Voltage between terminal No. 34 and earth, also between terminal No. 43 and earth. OK: System voltage Q: Is the check result normal? YES: Check and repair C-135 engine-A/T-ECU connector. NO: Go to Step 6 .
	STEP 6. Connector check: C-135 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Go to Step 7 . NO: Repair.
	STEP 7. Perform voltage measurement at C-135 engine-A/T-ECU connector.
	Measure engine-A/T-ECU terminal voltage. Ignition switch: ON Voltage between terminal No. 50 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 10 . NO: Go to Step 8 .
	STEP 8. Connector check: C-303 ignition switch connector
	Q: Is the check result normal? YES: Go to Step 9 . NO: Repair.
	STEP 9. Check ignition switch.
	Check ignition switch (Refer to GROUP 54A - Ignition Switch - Ignition Switch - Inspection ). Q: Is the check result normal? YES: Check intermediate connector C-106, C-202 and C-203, and repair if necessary. If intermediate connector is normal, check and repair harness between C-303 (terminal No. 2) ignition switch connector and C-135 (terminal No. 50) engine-A/T-ECU connector. Check output line for open/short circuit and damage. NO: Replace ignition switch.
	STEP 10. Perform voltage measurement at C-135 engine-A/T-ECU connector.
	Measure engine-A/T-ECU terminal voltage. Ignition switch: OFF Voltage between terminal No. 57 and earth. OK: System voltage Q: Is the check result normal? YES: Go to Step 11 . NO: Check and repair harness between B-17X (terminal No. 2) engine control relay connector and C-135 (terminal No. 57) engine-A/T-ECU connector. Check earthing line for open/short circuit.
	STEP 11. Check harness between B-17X (terminal No. 3 and No. 4) engine control relay connector and battery.
	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 12 . NO: Repair.
	STEP 12. Check harness between C-303 (terminal No. 2) ignition switch connector and C-135 (terminal No. 50) engine-A/T-ECU connector.
	NOTE: Before checking harness, check intermediate connectors C-106, C-202 and C-203 and repair if necessary. Check output line for damage. Q: Is the check result normal? YES: Go to Step 13 . NO: Repair.
	STEP 13. Check harness between C-135 (terminal No. 33 and No. 42) engine-A/T-ECU connector and body earth.
	Check earthing line for damage. Q: Is the check result normal? YES: Replace engine-A/T-ECU NO: Repair.