Inspection Procedure 4: The Starter is Impossible to Operate <A/T>

OPERATION

The power source is supplied from the battery to the starter connector terminal.
The battery voltage is applied to the starter relay connector terminal.
When the ignition switch-ST signal is input to the engine-ECU connector terminal ST, the engine-ECU connector terminal STRL turns ON the power transistor inside the unit, and makes the current flow into the starter relay connector terminal to turn ON the relay.
When the starter relay is turned ON, the current flows into the starter connector terminal from the starter relay connector terminal to drive the starter motor.

COMMENTS ON TROUBLE SYMPTOM

The failure could possibly be caused by the malfunction of the starter or starter system circuits.

PROBABLE CAUSES

Failed battery
Failed ignition switch <Vehicles without KOS>
Failed OSS-ECU <Vehicles with KOS>
Failed starter relay
Failed starter motor
Open/short circuit or harness damage in starter system circuit or loose connector contact.
Failed inhibitor switch
Failed ETACS-ECU
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check battery.

Check battery (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. M.U.T.-III data list

Item 40: Starter switch

OK:
ON (ignition switch: ST)
OFF (ignition switch: ON)

Q. Is the check result normal?

	Go to Step 13.

	Go to Step 3.

STEP 3. Perform voltage measurement at engine-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ST
Voltage between terminal ST and body earth.

OK: System voltage

Q. Is the check result normal?

	YES : Go to Step 8 <Vehicles without KOS>.

	YES : Go to Step 9 <Vehicles with KOS>.

	Go to Step 4.

STEP 4. Perform voltage measurement at ETACS-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ST
Voltage between terminal ST and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 7.

	NO : Go to Step 5 <Vehicles without KOS>.

	NO : Go to Step 6 <Vehicles with KOS>.

STEP 5. Check ignition switch itself.

Ignition switch connector check.
Check ignition switch itself (Refer to GROUP 54A - Ignition Switch - Ignition Switch - Ignition Switch Check ).

Q. Is the check result normal?

	Repair or replace the connector, or check and repair the harness between ignition switch connector terminal and ETACS-ECU connector terminal ST. Check power supply line for open/short circuit.

	Repair or replace the connector, or replace the ignition switch.

STEP 6. Check harness between OSS-ECU connector terminal STO and ETACS-ECU connector terminal ST.

Check power supply line for open/short circuit.

Q. Is the check result normal?

	Perform troubleshooting of OSS System (Refer to GROUP 42B - Troubleshooting <OSS-ECU> - Trouble Symptom Chart ).

	Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Continuity check on ETACS-ECU connectors

Disconnect connectors, and measure at ETACS-ECU side.
Continuity check between terminal ST and ST2

OK: Continuity

Q. Is the check result normal?

	Repair or replace the connector, or check and repair the harness between ETACS-ECU connector terminal ST2 and engine-ECU connector terminal ST. Check power supply line for open/short circuit.

	Repair or replace the connector, or replace the ETACS-ECU.

STEP 8. Check harness between ignition switch connector terminal and ETACS-ECU connector terminal ST.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 10.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 9. Check harness between OSS-ECU connector terminal STO and ETACS-ECU connector terminal ST.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 10.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 10. Continuity check on ETACS-ECU connectors

Disconnect connectors, and measure at ETACS-ECU side.
Continuity check between terminal ST and ST2

OK: Continuity

Q. Is the check result normal?

	Go to Step 11.

	Repair or replace the connector, or replace the ETACS-ECU.

STEP 11. Check harness between ETACS-ECU connector terminal ST2 and engine-ECU connector terminal ST.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 12.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 12. M.U.T.-III data list

Item 40: Starter switch

OK:
ON (ignition switch: ST)
OFF (ignition switch: ON)

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Replace the engine-ECU.

STEP 13. Check starter relay itself.

Starter relay connector check.
Check starter relay itself (Refer to GROUP 16 - Starting System - On-vehicle Service - Starter Relay Continuity Check ).

Q. Is the check result normal?

	Go to Step 14.

	Repair or replace the connector, or replace the starter relay.

STEP 14. Perform resistance measurement at starter relay connector.

Remove relay, and measure at relay box side.
Resistance between terminal earthing line and body earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 15.

	Repair or replace the connector, or check and repair harness between starter relay connector terminal and body earth. Check earthing line for open circuit and damage.

STEP 15. Check harness between engine-ECU connector terminal NTSW and starter relay connector terminal.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 16.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 16. Perform voltage measurement at starter relay connector.

Remove relay, and measure at relay box side.
Transmission: P or N range
Ignition switch: ST
Voltage between terminal engine-ECU STRL line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 21.

	NO : Go to Step 17.

STEP 17. Check inhibitor switch

Inhibitor switch connector check.
Check inhibitor switch (Refer to GROUP 23C - On-vehicle Service - A/T Control Component Check - Inhibitor Switch Check ).

Q. Is the check result normal?

	Go to Step 18.

	Repair or replace the connector, or replace the inhibitor switch.

STEP 18. Check harness between inhibitor switch connector terminal and starter relay connector terminal.

Check power supply line for open/short circuit.

Q. Is the check result normal?

	Go to Step 19.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 19. Check harness between engine-ECU connector terminal STRL and inhibitor switch connector terminal.

Check power supply line for open/short circuit.

Q. Is the check result normal?

	Go to Step 20.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 20. M.U.T.-III data list

Item 413: Starter relay

OK:
ON (ignition switch: ST)
OFF (ignition switch: ON)

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Replace the engine-ECU.

STEP 21. Perform voltage measurement at starter relay connector.

Remove relay, and measure at relay box side.
Voltage between terminal power supply line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 22.

	Repair or replace the connector, or check and repair harness between battery and starter relay connector terminal. Check power supply line for open/short circuit.

STEP 22. Perform voltage measurement at starter connector.

Disconnect connector, and measure at harness side.
Transmission: P or N range
Ignition switch: ST
Voltage between terminal output line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 26.

	Go to Step 23.

STEP 23. Check harness between starter relay connector terminal and starter connector terminal.

Check output line for open/short circuit.

Q. Is the check result normal?

	YES : Go to Step 24.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 24. Check inhibitor switch

Inhibitor switch connector check.
Check inhibitor switch (Refer to GROUP 23C - On-vehicle Service - A/T Control Component Check - Inhibitor Switch Check ).

Q. Is the check result normal?

	Go to Step 25.

	Repair or replace the connector, or replace the inhibitor switch.

STEP 25. Check harness between inhibitor switch connector terminal and starter relay connector terminal.

Check power supply line for damage.

Q. Is the check result normal?

	Repair or replace the connector, or check and repair harness between engine-ECU connector terminal STRL and inhibitor switch connector terminal. Check power supply line for damage.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 26. Check harness between battery and starter relay connector terminal.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 27.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 27. Check harness between starter relay connector terminal and starter connector terminal.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 28.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 28. Perform voltage measurement at starter terminal.

Disconnect terminal, and measure at harness side.
Voltage between terminal power supply line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 29.

	Repair or replace the terminal, or check and repair harness between battery and starter terminal. Check power supply line for open/short circuit.

STEP 29. Check harness between battery and starter terminal.

Check power supply line for damage.

Q. Is the check result normal?

	Replace the starter.

	Repair or replace the terminal, or repair the damaged harness wire.