Inspection Procedure 31
Ignition Circuit:
Connectors:
CIRCUIT OPERATION
- 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 1, 2 and 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 2. Then the primary current flows to the ignition coil.
TROUBLESHOOTING HINTS
The most likely causes for this case:
- Malfunction of the ignition switch.
- Malfunction of the ignition power transistor.
- Improper connector contact, open circuit or short-circuited harness wire.
- Malfunction of the PCM.
DIAGNOSIS
STEP 1. Check the power supply line at the ignition coil connectors A-44, A-45 and A-46.
1. Disconnect connectors A-44, A-45, and A-46 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Connect terminal 1 and ground via a 20-ohms resistor.
Measure the current at this time.
- The current should be 0.5 ampere or more.
4. Turn the ignition switch "OFF".
If within specifications, go to Step 2.
If not within specifications, repair the harness wire and connector between the ignition coil and the ignition switch. Refer to vehicle level Testing and Inspection. Then confirm that the malfunction symptom is eliminated.
STEP 2. Check the ground line at the ignition power transistor connector A-05.
1. Disconnect connector A-05 and measure at the harness side.
2. Check for the continuity between terminal 4 and ground.
- There should be continuity (0 ohms).
If continuity, go to Step 3.
If no continuity, repair the harness wire between the ignition power transistor connector A-05 and ground. Then confirm that the malfunction symptom is eliminated.
STEP 3. Check the ignition coil.
Refer to Ignition System.
If correct, go to Step 4.
If incorrect, replace the ignition coil. Then confirm that the malfunction symptom is eliminated.
STEP 4. Check the ignition power transistor.
Refer to Ignition System.
If correct, go to Step 5.
If incorrect, replace the ignition power transistor. Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the power supply line at the ignition power transistor connector A-06.
1. Disconnect connector A-06 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Connect terminals 11, 12, 13 and ground via a 20 ohms resistor. Measure the current at this time.
- The current should be 0.5 ampere or more.
4. Turn the ignition switch "OFF".
If not within specifications, go to Step 6.
If within specifications, go to Step 7.
STEP 6. Check the harness wire between the ignition coil connectors A-44, A-45, A-46 and the ignition power transistor connector A-06.
If the wire between the ignition coil connectors A-44, A-45, A-46 and the ignition power transistor connector A-06 is damaged, repair it.
If the wire between the ignition coil connectors A-44, A-45, A-46 and the ignition power transistor connector A-06 is not damaged, repair or replace the ignition coil connectors A-44, A-45, A-46. Refer to vehicle level Testing and Inspection.
Then confirm that the malfunction symptom is eliminated.
STEP 7. Check the circuit at the ignition power transistor connector A-05.
1. Disconnect connector A-05 and measure at the harness side.
2. Crank the engine.
3. Measure voltage between terminals 1, 2, 3 and ground.
- Voltage should be between 0.5 and 4.0 volts.
If not within specifications, go to Step 8. If within specifications, go to Step 10.
STEP 8. Check the harness wire between the ignition power transistor connector A-05 (terminals 1, 2, 3) and the PCM connector C-89 (terminals 11, 12, 13).
If the wire between the ignition power transistor connector A-05 and the PCM connector C-89 is not damaged, go to Step 9.
If the wire between the ignition power transistor connector A-05 and the PCM connector C-89 is damaged, repair it.
Then confirm that the malfunction symptom is eliminated.
STEP 9. Check harness connector C-89 at the PCM for damage.
If harness connector C-89 is damaged, repair or replace it.
Refer to vehicle level Testing and Inspection.
If harness connector C-89 is in good condition, replace the PCM.
Then confirm that the malfunction symptom is eliminated.
STEP 10. Check the circuit at ignition power transistor connector A-05.
1. Disconnect connector A-05 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Measure the voltage between terminal 6 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).
4. Turn the ignition switch "OFF".
STEP 11. Check the circuit at ignition power transistor connector A-05.
1. Disconnect connector A-05 and measure at the harness side.
2. Turn the ignition switch "ON".
3. Measure the voltage between terminal 5 and ground.
- Voltage should be 4 volts or more.
4. Turn the ignition switch "OFF".
If 4 volts or more, go to Step 12.
If less than 4 volts, go to Step 13.
STEP 12. Check harness connector A-05 at the ignition power transistor for damage.
If harness connector A-05 is damaged, repair or replace it.
Refer to vehicle level Testing and Inspection.
If harness connector A-05 is in good condition, replace the ignition power transistor.
Then check that the malfunction is eliminated.
STEP 13. Check the harness wire between ignition power transistor connector A-05 and PCM connector C-90.
If the wire between ignition power transistor connector A-05 and PCM connector C-90 is not damaged, go to Step 14.
If the wire between ignition power transistor connector A-05 and PCM connector C-90 is damaged, repair it. Then check that the malfunction is eliminated.
STEP 14. Check harness connector C-90 at the PCM for damage.
If harness connector C-90 is damaged, repair or replace it.
Refer to vehicle level Testing and Inspection.
If harness connector C-90 is in good condition, replace the PCM. Then check that the malfunction is eliminated.