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Inspection procedure 24: 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 (terminal No. 1) 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>
  • 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.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tool:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: V.C.I.
    • MB991827: USB Cable
    • MB991910: Main Harness A
STEP 1. Using scan tool MB991958, check data list item 79: Cranking Signal.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to the data reading mode for item 79, Cranking Signal.
  • When the engine is stopped, "OFF" should be displayed.
  • When the engine is cranked, "ON" should be displayed.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the operating properly?
Go to Step 16.
Go to Step 2.
 
STEP 2. Check harness connector C-403, C-415 at ETACS-ECU for damage.
Are the harness connectors in good condition?
Go to Step 3.
Repair or replace them. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 3. Measure the ignition switch-ST signal voltage at ETACS-ECU harness side connector C-415.
(1) Disconnect the connector C-415 and measure at the harness side.
(2) Turn the ignition switch to the "START" position.
(3) Measure the voltage between terminal No. 7 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 8. <Vehicles without KOS>
Go to Step 10. <Vehicles with KOS>
Go to Step 4. <Vehicles without KOS>
Go to Step 6. <Vehicles with KOS>
 
STEP 4. Check harness connector C-309 at ignition switch for damage.
Is the harness connector in good condition?
Go to Step 5.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 5. 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 harness wire between ignition switch connector C-309 (terminal No. 5) and ETACS-ECU connector C-415 (terminal No. 7) because of open circuit or short circuit to ground. Then confirm that the malfunction symptom is eliminated.
 
STEP 6. Check harness connector C-14 at OSS-ECU connector for damage.
Is the harness connector in good condition?
Go to Step 7.
Repair or replace the it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 7. Check for open circuit and short circuit to ground between OSS-ECU connector C-14 (terminal No. 23) and ETACS-ECU connector C-415 (terminal No. 7).
Is the harness wire in good condition?
Perform troubleshooting of OSS System (Refer to GROUP 42B - Troubleshooting - Trouble Symptom Chart ).
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 8. Check harness connector C-309 at ignition switch for damage.
Is the harness connector in good condition?
Go to Step 9.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 9. Check for harness damage between ignition switch connector C-309 (terminal No. 5) and ETACS-ECU connector C-415 (terminal No. 7).
Is the harness wire in good condition?
Go to Step 12.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 10. Check harness connector C-14 at OSS-ECU connector for damage.
Is the harness connector in good condition?
Go to Step 11.
Repair or replace the it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 11. Check for harness damage between OSS-ECU connector C-14 (terminal No. 23) and ETACS-ECU connector C-415 (terminal No. 7).
Is the harness wire in good condition?
Go to Step 12.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 12. Check the continuity at ETACS-ECU side connector C-403 and C-415.
(1) Disconnect the connector C-403, C-415 and measure at the ETACS-ECU side.
(2) Check for the continuity between connector C-403 (terminal No. 15) and connector C-415 (terminal No. 7).
  • Continuity.
Does continuity exist?
Go to Step 13.
Replace the ETACS-ECU. Then confirm that the malfunction symptom is eliminated.
 
STEP 13. Check harness connector B-27 at ECM for damage.
Is the harness connector in good condition?
Go to Step 14.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 14. Check for open circuit, short circuit to ground and harness damage between ETACS-ECU connector C-403 (terminal No. 15) and ECM connector B-27 (terminal No. 105).
Is the harness wire in good condition?
Go to Step 15.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 15. Using scan tool MB991958, check data list item 79: Cranking Signal.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item 79, Cranking Signal.
  • 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?
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 .
Replace the ECM (Refer to, Removal and Installation ). Then confirm that the malfunction symptom is eliminated.
 
STEP 16. Check harness connector A-31X at starter relay for damage.
Is the harness connector in good condition?
Go to Step 17.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 17. Check the starter relay.
(1) Remove the starter relay.
(2) Check for continuity between the starter relay terminals No. 1 and No. 2.
  • There should be continuity.
(3) Use jumper wires to connect starter relay terminal No. 2 to the positive battery terminal and terminal No. 1 to the negative battery terminal.
(4) Check for continuity between the starter relay terminals No. 3 and No. 4 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 18.
Replace the starter relay. Then confirm that the malfunction symptom is eliminated.
 
STEP 18. Check the continuity at starter relay harness side connector A-31X.
(1) Disconnect the connector A-31X and measure at the harness side.
(2) Check for the continuity between terminal No. 1 and ground.
  • Continuity (2 ohms or less).
Does continuity exist?
Go to Step 19.
Repair harness wire between starter relay connector A-31X (terminal No. 1) and ground because of open circuit or harness damage. Then confirm that the malfunction symptom is eliminated.
 
STEP 19. Measure the power supply voltage at starter relay harness side connector A-31X.
(1) Disconnect the connector A-31X and measure at the harness side.
(2) Put the transmission range into "P" or "N".
(3) Turn the ignition switch to the "START" position.
(4) Measure the voltage between terminal No. 2 and ground.
  • Voltage should be battery positive voltage.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 28.
Go to Step 20.
 
STEP 20. Check harness connector B-122 at transmission range switch for damage.
Is the harness connector in good condition?
Go to Step 21.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 21. Check the transmission range switch.
Refer to GROUP 23A, On-vehicle Service - CVT Control Component Check - Transmission Range Switch Check .
Are there any abnormalities?
Replace the transmission range switch. Then confirm that the malfunction symptom is eliminated.
Go to Step 22.
 
STEP 22. Measure the power supply voltage at transmission range switch harness side connector B-122.
(1) Disconnect the connector B-122 and measure at the harness side.
(2) Turn the ignition switch to the "START" position.
(3) Measure the voltage between terminal No. 10 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 26.
Go to Step 23.
 
STEP 23. Check harness connector B-27 at ECM for damage.
Is the harness connector in good condition?
Go to Step 24.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 24. Check for open circuit and short circuit to ground between ECM connector B-27 (terminal No. 106) and transmission range switch connector B-122 (terminal No. 10).
noteCheck harness after checking intermediate connector A-17. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
Is the harness wire in good condition?
Go to Step 25.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 25. Using scan tool MB991958, check data list item 102: Starter Relay.
(1) Turn the ignition switch to the "ON" position.
(2) Set scan tool MB991958 to the data reading mode for item 102, Starter Relay.
  • 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?
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 .
Replace the ECM (Refer to, Removal and Installation ). Then confirm that the malfunction symptom is eliminated.
 
STEP 26. Check for open circuit and short circuit to ground between transmission range switch connector B-122 (terminal No. 7) and starter relay connector A-31X (terminal No. 2).
noteCheck harness after checking intermediate connector A-17. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
Is the harness wire in good condition?
Go to Step 27.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 27. Check harness connector B-26 at ECM for damage.
Is the harness connector in good condition?
Check harness connector A-17 at intermediate connector for damage, and repair or replace as required. Refer to GROUP 00E, Harness Connector Inspection . If intermediate connector is in good condition, repair harness wire between ECM connector B-26 (terminal No. 6) and starter relay connector A-31X (terminal No. 2) because of short circuit to ground. Then confirm that the malfunction symptom is eliminated.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 28. Check harness connector B-112 at starter for damage.
Is the harness connector in good condition?
Go to Step 29.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 29. Measure the power supply voltage at starter harness side connector B-112.
(1) Disconnect the connector B-112 and measure at the harness side.
(2) Turn the ignition switch to the "START" position.
(3) Measure the voltage between terminal No. 1 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 34.
Go to Step 30.
 
STEP 30. Measure the power supply voltage at starter relay harness side connector A-31X.
(1) Disconnect the connector A-31X and measure at the harness side.
(2) Measure the voltage between terminal No. 4 and ground.
  • Voltage should be battery positive voltage.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 31.
Repair harness wire between fusible link (24) and starter relay connector A-31X (terminal No. 4) because of open circuit or short circuit to ground. Then confirm that the malfunction symptom is eliminated.
 
STEP 31. Check for open circuit and short circuit to ground between starter relay connector A-31X (terminal No. 3) and starter connector B-112 (terminal No. 1)
noteCheck harness after checking intermediate connectors A-17 and B-114. If intermediate connectors are damaged, repair or replace them. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
Is the harness wire in good condition?
Go to Step 32.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 32. Check harness connector B-27 at ECM and harness connector B-122 at transmission range switch for damage.
Are the harness connectors in good condition?
Go to Step 33.
Repair or replace them. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 33. Check for harness damage between ECM connector B-27 (terminal No. 106) and transmission range switch connector B-122 (terminal No. 10).
noteCheck harness after checking intermediate connector A-17. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
Is the harness wire in good condition?
Check harness connector A-17 at intermediate connector for damage, and repair or replace as required. Refer to GROUP 00E, Harness Connector Inspection . If intermediate connector is in good condition, repair harness wire between transmission range switch connector B-122 (terminal No. 7) and starter relay connector A-31X (terminal No. 2) because of harness damage. Then confirm that the malfunction symptom is eliminated.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 34. Check for harness damage between starter relay connector A-31X (terminal No. 3) and starter connector B-112 (terminal No. 1)
noteCheck harness after checking intermediate connectors A-17 and B-114. If intermediate connectors are damaged, repair or replace them. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
Is the harness wire in good condition?
Go to Step 35.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 35. Check for harness damage between fusible link (24) and starter relay connector A-31X (terminal No. 4)
Is the harness wire in good condition?
Go to Step 36.
Repair it. Then confirm that the malfunction symptom is eliminated.
 
STEP 36. Check harness connector B-113 at starter for damage.
Is the harness connector in good condition?
Go to Step 37.
Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then confirm that the malfunction symptom is eliminated.
 
STEP 37. Check for open circuit, short circuit to ground and harness damage between battery and starter connector B-113 (terminal No. 1)
Is the harness wire in good condition?
Replace the starter. Then confirm that the malfunction symptom is eliminated.
Repair it. Then confirm that the malfunction symptom is eliminated.