Inspection Procedure 4: Starting Impossible (starter not operative)

OPERATION

The power source is supplied from the battery to the starter 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

Failure is possibly caused by malfunction of starter or starter system circuits.

PROBABLE CAUSES

Failed battery
Failed KOS&OSS-ECU
Failed starter relay
Failed starter motor
Open/short circuit or harness damage in starter system circuit or loose connector contact.
Failed inhibitor switch
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 79: Cranking signal

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

Q. Is the check result normal?

	Go to Step 7.

	Go to Step 3.

STEP 3. Voltage measurement at engine-ECU connector (ST terminal).

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Ignition switch: "ST"

(3)Check the voltage between the engine-ECU connector (ST terminal) and body earth.
OK: System voltage

Q. Is the check result normal?

	YES : Go to Step 5.

	Go to Step 4.

STEP 4. Check of short to earth, and open circuit in ST line between KOS&OSS-ECU connector and engine-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 5. Check of harness damage in ST line between KOS&OSS-ECU connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 6.

	Repair the connector(s) or wiring harness.

STEP 6. M.U.T.-III data list

Item 79: Cranking signal

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 7. Check starter relay itself.

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 8.

	Replace the starter relay.

STEP 8. Resistance measurement at starter relay connector (earth line).

(1)Remove relay, and measure at the relay box side.

(2)Check the resistance between the starter relay connector (earth line) and body earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 9.

	Repair or replace the connector(s), or check and repair the harness of open circuit and damage in earth line between starter relay connector and body earth.

STEP 9. Voltage measurement at starter relay connector (STRL line).

(1)Remove relay, and measure at the relay box side.

(2)Transmission: P or N range

(3)Ignition switch: "ST"

(4)Check the voltage between the starter relay connector (STRL line) and body earth.
OK: System voltage

Q. Is the check result normal?

	Go to Step 15.

	Go to Step 10.

STEP 10. Check inhibitor switch

Check inhibitor switch (Refer to GROUP 23A - On-vehicle Service - Essential Service - Inhibitor Switch Continuity Check ).

Q. Is the check result normal?

	Go to Step 11.

	Replace the inhibitor switch.

STEP 11. Check of short to earth, and open circuit in STRL line between inhibitor switch connector and starter relay connector.

Q. Is the check result normal?

	Go to Step 12.

	Repair the connector(s) or wiring harness.

STEP 12. Check of short to earth, and open circuit in STRL line between engine-ECU connector and inhibitor switch connector.

Q. Is the check result normal?

	Go to Step 13.

	Repair the connector(s) or wiring harness.

STEP 13. Check of short circuit to earth in STCD line between engine-ECU connector and starter relay connector.

Q. Is the check result normal?

	Go to Step 14.

	Repair the connector(s) or wiring harness.

STEP 14. M.U.T.-III data list

Item 102: 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 15. Voltage measurement at starter relay connector (power supply line).

(1)Remove relay, and measure at the relay box side.

(2)Check the voltage between the starter relay connector (power supply line) and body earth.
OK: System voltage

Q. Is the check result normal?

	Go to Step 16.

	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 starter relay connector

STEP 16. Voltage measurement at starter connector (power supply line).

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Transmission: P or N range

(3)Ignition switch: "ST"

(4)Check the voltage between the starter connector (power supply line) and body earth.
OK: System voltage

Q. Is the check result normal?

	Go to Step 20.

	Go to Step 17.

STEP 17. Check of short to earth, and open circuit in power supply line between starter relay connector and starter connector.

Q. Is the check result normal?

	Go to Step 18.

	Repair the connector(s) or wiring harness.

STEP 18. Check inhibitor switch

Check inhibitor switch (Refer to GROUP 23A - On-vehicle Service - Essential Service - Inhibitor Switch Continuity Check ).

Q. Is the check result normal?

	Go to Step 19.

	Replace the inhibitor switch.

STEP 19. Check of harness damage in STRL line between inhibitor switch connector and starter relay connector.

Q. Is the check result normal?

	Repair or replace the connector(s), or check and repair the harness of damage in STRL line between engine-ECU connector and inhibitor switch connector.

	Repair the connector(s) or wiring harness.

STEP 20. Check of harness damage in power supply line between battery and starter relay connector.

Q. Is the check result normal?

	Go to Step 21.

	Repair the damaged harness wire.

STEP 21. Check of harness damage in power supply line between starter relay connector and starter connector.

Q. Is the check result normal?

	Go to Step 22.

	Repair the connector(s) or wiring harness.

STEP 22. Voltage measurement at starter terminal (power supply line).

(1)Disconnect the terminal, and measure at the wiring harness side.

(2)Check the voltage between the starter terminal (power supply line) and body earth.
OK: System voltage

Q. Is the check result normal?

	Go to Step 23.

	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 starter terminal

STEP 23. Check of harness damage in power supply line between battery and starter terminal.

Q. Is the check result normal?

	Replace the starter.

	Repair the connector(s) or wiring harness.