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Inspection procedure 23: Ignition switch-ST system and starter relay system
 
 
 
 
CIRCUIT OPERATION
  • If the selector lever is moved to "P" or "N" range and the ignition switch is turned to "START" position, battery positive voltage is supplied to starter relay coil. With this, the starter relay turns "ON" the battery positive voltage is supplied to the starter motor from the battery.
 
 
COMMENT
  • Faulty starting system and the related circuit are suspected to be the causes.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this case: )
  • Battery failed.
  • Ignition switch failed. <Vehicles without KOS>
  • KOS&OSS-ECU failed. <Vehicles with KOS>
  • Starter relay failed.
  • Starter motor failed.
  • Open or shorted starting system circuit, harness damage, or connector damage.
  • Transmission range switch failed.
  • ETACS-ECU failed.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Check the battery.
Refer to GROUP 54A, Battery - On-vehicle Service - Battery Test .
Are there any abnormalities?
Replace the battery. Then confirm that the malfunction symptom is eliminated.
: Go to Step 3.
: Go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-IIISE), read the other system diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn the ignition switch to the "ON" position.
(3) Read the KOS&OSS-DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the KOS&OSS-DTC set?
Refer to GROUP 42B, Diagnosis - Diagnostic Trouble Code Chart .
Go to Step 3.
 
STEP 3. Using scan tool (M.U.T.-IIISE), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is any DTC set?
Refer to Diagnostic Trouble Code Chart .
Go to Step 4.
 
STEP 4. Using scan tool (M.U.T.-IIISE), check data list item 87: Neutral Switch.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool (M.U.T.-IIISE) to the data reading mode for item 87, Neutral Switch.
  • When the selector lever is "P" or "N", "ON" should be displayed.
  • When the selector lever is except "P" and "N", "OFF" should be displayed.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the operating properly?
Go to Step 10.
Go to Step 5.
 
STEP 5. Check the transmission range switch.
Refer to GROUP 23A, On-vehicle Service - Essential Service - Transmission Range Switch Continuity Check .
Are there any abnormalities?
Replace the transmission range switch. Then confirm that the malfunction symptom is eliminated.
Go to Step 6.
 
STEP 6. Measure the power supply voltage at transmission range switch harness side connector.
(1) Disconnect the transmission range switch connector and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal MFI relay side power supply line and ground.
  • Voltage should be battery positive voltage
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 7.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in power supply line between MFI relay connector and transmission range switch connector. Then confirm that the malfunction symptom is eliminated.
 
STEP 7. Check of harness damage in power supply line between MFI relay connector and transmission range switch connector.
Is the harness wire in good condition?
Go to Step 8.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 8. Check of short circuit, open circuit and harness damage in IHB line between transmission range switch connector and ECM connector.
Is the harness wire in good condition?
Go to Step 9.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 9. Check the malfunction symptoms.
Does the malfunction symptom persist?
Replace the ECM (Refer to Removal and Installation ). Then confirm that the malfunction symptom is eliminated.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 10. Using scan tool (M.U.T.-IIISE), check data list item 79: Cranking signal (ignition switch-ST).
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool (M.U.T.-IIISE) to the data reading mode for item 79, Cranking Signal (ignition switch-ST).
  • When the engine is stopped, "OFF" should be displayed.
  • When the engine is cranked, "ON" should be displayed.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the operating properly?
Go to Step 18.
Go to Step 11.
 
STEP 11. Measure the ignition switch-ST signal voltage at ETACS-ECU harness side connector.
(1) Disconnect the ETACS-ECU connector and measure at the harness side.
(2) Turn the ignition switch to the "START" position.
(3) Measure the voltage between terminal ST1 and ground.
  • Voltage should be battery positive voltage
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
: Go to Step 14.
: Go to Step 15.
: Go to Step 12.
: Go to Step 13.
 
STEP 12. Check the ignition switch
Refer to GROUP 54A, Ignition Switch - Inspection - Ignition Switch Continuity Check .
Are there any abnormalities?
Replace the ignition switch. Then confirm that the malfunction symptom is eliminated.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in ST1 line between ignition switch connector and ETACS-ECU connector. Then confirm that the malfunction symptom is eliminated.
 
STEP 13. Check of short to ground and open circuit in ST1 line between KOS&OSS-ECU connector and ETACS-ECU connector.
Is the harness wire in good condition?
Check the KOS&OSS System. Refer to GROUP 42B, Diagnosis - Trouble Symptom Chart .
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 14. Check of harness damage in ST1 line between ignition switch connector and ETACS-ECU connector.
Is the harness wire in good condition?
Go to Step 16.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 15. Check of harness damage in ST1 line between KOS&OSS-ECU connector and ETACS-ECU connector.
Is the harness wire in good condition?
Go to Step 16.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 16. Check the continuity at ETACS-ECU side connectors.
(1) Disconnect the ETACS-ECU connector and measure at the ETACS-ECU side.
(2) Check for the continuity between terminal ST1 and ST2.
  • Continuity (2 ohms or less).
Does continuity exist?
Go to Step 17.
Replace the ETACS-ECU. Then confirm that the malfunction symptom is eliminated.
 
STEP 17. Check of short circuit, open circuit and harness damage in ST2 line between ETACS-ECU connector and ECM connector.
Is the harness wire in good condition?
Go to Step 9.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 18. Check the starter relay.
(1) Remove the starter relay.
(2) Check for continuity between the starter relay coil terminals.
  • There should be continuity.
(3) Use jumper wires to connect starter relay terminal STHI line to the positive battery terminal and terminal STLO line to the negative battery terminal.
(4) Check for continuity between the starter relay switch terminals while connecting and disconnecting the jumper wire at the negative battery terminal.
  • Continuity (2 ohms or less). (Negative battery terminal connected)
  • Should be open loop. (Negative battery terminal disconnected)
(5) Install the starter relay.
Is the measured resistance normal?
Go to Step 19.
Replace the starter relay. Then confirm that the malfunction symptom is eliminated.
 
STEP 19. Measure the power supply voltage at starter harness side connector.
(1) Disconnect the starter motor magnetic switch connector and measure at the harness side.
(2) Turn the ignition switch to the "START" position.
(3) Measure the voltage between terminal starter relay side power supply line and ground.
  • Voltage should be battery positive voltage
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 21.
Go to Step 20.
 
STEP 20. Measure the power supply voltage at starter relay harness side connector.
(1) Remove the starter relay and measure at the relay box side.
(2) Measure the voltage between terminal fusible link side power supply line and ground.
  • Voltage should be battery positive voltage
Is battery positive voltage (approximately 12 volts) present?
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in power supply line between starter relay connector and starter connector. Then confirm that the malfunction symptom is eliminated.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in power supply line between fusible link and starter relay connector. Then confirm that the malfunction symptom is eliminated.
 
STEP 21. Check of harness damage in power supply line between starter relay connector and starter connector.
Is the harness wire in good condition?
Go to Step 22.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 22. Check of harness damage in power supply line between fusible link and starter relay connector.
Is the harness wire in good condition?
Go to Step 23.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 23. Check of short to ground, open circuit and harness damage in power supply line between battery and starter terminal.
Is the harness wire in good condition?
Go to Step 24.
Repair the connector(s) or wiring harness. Then confirm that the malfunction symptom is eliminated.
 
STEP 24. Check starter motor operation.
Refer to GROUP 16, Starting System - Starter Motor Assembly - Starter Motor Assembly Inspection .
Is the starter motor normal?
Go to Step 9.
Replace the starter. Then confirm that the malfunction symptom is eliminated.