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Home >> Mitsubishi >> 2003 >> Montero Sport V6-3.5L SOHC >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Symptom Related Diagnostic Procedures >> Inspection Procedure 31
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Inspection Procedure 31

Ignition Circuit System.

Ignition Circuit Part 1:




Ignition Circuit Part 2:






COMMENT
- The battery positive voltage is applied on the ignition coil by the ignition switch-IG.
- When the PCM turns the power transistor in the PCM "OFF," battery positive voltage is applied on the ignition power transistor (terminals No. 1, No. 2 and No. 3), and the ignition power transistor turns "ON."
- When the ignition power transistor turns "ON", the ignition coil's primary circuit is grounded by the ignition power transistor terminal No. 4. Then the primary current flows to the ignition coil.

TROUBLESHOOTING HINTS (The most likely causes for this case: )
- Malfunction of the ignition coil.
- Malfunction of the ignition power transistor.
- Improper connector contact, open circuit or short-circuited harness wire.
- Malfunction of the PCM.

DIAGNOSIS




STEP 1. Check harness connectors A-44, A-45, A-46 at ignition coil for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 2.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

STEP 2. Check the ignition coil.
Refer to Ignition System - Ignition Coil Check.

Q: Are there any abnormalities?

YES: Go to Step 3.

NO: Replace the ignition coil. Then confirm that the malfunction symptom is eliminated.




STEP 3. Check harness connectors A-05, A-06 at ignition power transistor for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 4.

NO: Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

STEP 4. Check the ignition power transistor.
Refer to Ignition System - Ignition Coil Power Transistor Continuity Check.

Q: Are there any abnormalities?

YES: Go to Step 5.

NO: Replace the ignition power transistor. Then confirm that the malfunction symptom is eliminated.

STEP 5. Measure the power supply voltage at ignition coil connectors A-44, A-45, A-46.




1. Disconnect the connectors A-44, A-45, A-46 and measure at the harness side.
2. Turn the ignition switch to the "ON" 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.

Q: Is battery positive voltage (approximately 12 volts) present?

YES: Go to Step 6.

NO: Check harness connector D-08 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector D-08 is in good condition, repair harness wire between ignition switch connector D-15 (terminal No. 2) and ignition coil connectors A-44, A-45, A-46 (terminal No. 1). Then confirm that the malfunction symptom is eliminated.

STEP 6. Measure the power supply voltage at ignition power transistor connector A-06.




1. Disconnect the connector A-06 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminals No. 11, No. 12, No. 13 and ground.
- Voltage should be battery positive voltage.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is battery positive voltage (approximately 12 volts) present?

YES: Go to Step 7.

NO: Repair harness wire between ignition coil connectors A-44, A-45, A-46 (terminal No. 2) and ignition power transistor connector A-06 (terminals No. No. 11, No. 12, No. 13). Then confirm that the malfunction symptom is eliminated.

STEP 7. Measure the power supply voltage at ignition power transistor connector A-05.




1. Disconnect the connector A-05 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal No. 6 and ground.
- Voltage should be battery positive voltage.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is battery positive voltage (approximately 12 volts) present?

YES: Go to Step 8.

NO: Check harness connector D-08 at intermediate connector for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector D-08 is in good condition, repair harness wire between ignition switch connector D-15 (terminal No. 2) and ignition power transistor connector A-05 (terminal No. 6). Then confirm that the malfunction symptom is eliminated.

STEP 8. Check for continuity at ignition power transistor harness side connector A-05.




1. Disconnect the connector A-05 and measure at the harness side.




2. Check for the continuity between terminal No. 4 and ground.
- Should be less than 2 Ohms.

Q: Does continuity exist?

YES: Go to Step 9.

NO: Repair harness wire between ignition power transistor connector A-05 (terminal No. 4) and ground. Then confirm that the malfunction symptom is eliminated.

STEP 9. Measure the circuit at ignition power transistor connector A-05.




1. Disconnect the connector A-05 and measure at the harness side.
2. Crank the engine.




3. Measure the voltage between terminals No. 1, No. 2, No. 3 and ground.
- Voltage should be between 0.5 and 4.0 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is battery positive voltage (approximately 12 volts) present?

YES: Go to Step 12.

NO: Go to Step 10.




STEP 10. Check harness connector C-89 at PCM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 11.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.







STEP 11. Check for open circuit between ignition power transistor connector A-05 (terminals No. 1, No. 2, No. 3) and PCM connector C-89 (terminals No. 11, No. 12, No. 13).

Q: Is the harness wire in good condition?

YES: Replace the PCM. Then confirm that the malfunction symptom is eliminated.

NO: Repair it. Then confirm that the malfunction symptom is eliminated.

STEP 12. Measure the circuit at ignition power transistor connector A-05.




1. Disconnect the connector A-05 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal No. 5 and ground.
- Voltage should be 4 volts or more.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage 4 volts or more?

YES: Replace the ignition power transistor. Then confirm that the malfunction symptom is eliminated.

NO: Go to Step 13.




STEP 13. Check harness connector C90 at PCM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 14.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.







STEP 14. Check for open circuit between ignition power transistor connector A-05 (terminal No. 5) and PCM connector C-90 (terminal No. 43).

NOTE: Check harness after checking intermediate connector C-71. If intermediate connector is damaged, repair or replace them. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.

Q: Is the harness wire in good condition?

YES: Replace the PCM. Then confirm that the malfunction symptom is eliminated.

NO: Repair it. Then confirm that the malfunction symptom is eliminated.

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