Inspection Procedure 33

CIRCUIT OPERATION
- The ignition coil is energized by battery voltage from the ignition switch through the ignition failure sensor.
- When the ECM or PCM turns off its internal power transistor, battery positive voltage is applied to the ignition power transistor (terminal 3) inside the ignition coil, causing the ignition power transistor to be turned on.
- If the ignition power transistor is turned on, the primary circuit of the ignition coil is energized by grounding the ignition coil through terminal 2, causing the primary current to flow to the ignition coil.

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

WIRING DIAGRAM

CONNECTORS

DIAGNOSIS

STEP 1. Using the analyzer, check the ignition failure sensor.
1. Disconnect the ignition failure sensor connector B-01, and connect the test harness special tool MB991658 between the disconnected connectors (All terminals should be connected).

2. Connect the analyzer special patterns pickup to the ignition failure sensor-side connector terminal 3.
3. Crank the engine or run it at idle.

4. Inspect the waveform.
- The waveform should show a normal pattern similar to the illustration.
5. Stop the engine.
If the waveform does not show a normal pattern, go to Step 2.
If a normal waveform is shown, go to Step 11.

STEP 2. Check the ignition failure sensor.
Refer to Ignition System.
If correct, go to Step 3.
If incorrect, replace the ignition failure sensor. 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 power transistor. Then confirm that the malfunction symptom is eliminated.

STEP 4. Check the power supply line at ignition failure sensor connector B-01.
1. Disconnect connector B-01 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Connect terminal 4 to ground via a 20 Ohm resistor. Measure the current at this time.
- The current should be 0.5 amperes or more.
4. Turn the ignition switch off.
If within the specifications, go to Step 5.
If not within specification, repair the harness wire and connector between the ignition failure sensor and ignition switch. Refer to Harness Connector Inspection >. Then confirm that the malfunction symptom is eliminated.

STEP 5. Power supply line at ignition coil connectors B-39 and B-23.
1. Disconnect connectors B-09 and B-23 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Connect terminal 1 and ground via a 20 Ohm resistor. Measure the current at this time.
- The current should be 0.5 amperes or more.
4. Turn the ignition switch "OFF."
If not within the specifications, go to Step 6. If within the specifications, go to Step 7.

STEP 6. Check the harness wire between ignition failure sensor connector B-01 and ignition coil connectors B-39 and B-23.
If the wire between ignition failure sensor connector B-01 and ignition coil connectors B-09 and B-23 is damaged, replace it.
If the wire between ignition failure sensor connector B-01 and ignition coil connectors B-09 and B-23 is not damaged, repair or replace ignition failure sensor connector B-01. Refer to Harness Connector Inspection >.
Then confirm that the malfunction symptom is eliminated.

STEP 7. Check the ground line at ignition coil connectors B-09 and B-23.
1. Disconnect connectors B-09 and B-23 and measure at the harness side.
2. Check for continuity between terminal 2 and ground.
- There should be continuity (0 Ohm)
If continuity, go to Step 8.
If no continuity, repair the harness wire between ignition coil connectors B-09 and B-23 and ground. Then confirm that the malfunction symptom is eliminated.

STEP 8. Check the circuits at ignition coil connectors B-39 and B-23.
1. Disconnect connectors B-09 and B-23 and measure at the harness side.
2. Crank the engine or run it at idle.
3. Measure voltage between terminal 3 and ground.
- Voltage should be between 0.3 and 3.0 volts.
If not within the specifications, go to Step 9.
If within the specifications, repair or replace the ignition failure sensor connector B-01. Refer to Harness Connector Inspection >. Then confirm that the malfunction symptom is eliminated.

STEP 9. Check the harness wire between ignition coil connectors B-09 and B-23 and ECM connector C-35 or PCM connector C-39 .
If the wires between ignition coil connectors B-09, B-23 and ECM connector C-35 or PCM connector C-39 are not damaged, go to Step 10.
If the wires between ignition coil connectors B-09, B-23 and ECM connector C-35 or PCM connector C-39 are damaged, repair them. Then confirm that the malfunction symptom is eliminated.

STEP 10. Check harness connector C-35 at the ECM connector or harness connector C-39 at the PCM connector for damage.
If harness connector C-35 or C-39 is damaged, repair or replace it. Refer to Harness Connector Inspection >.
If harness connector C-35 or C-39 is in good condition, replace the ECM or PCM .
Then confirm that the malfunction symptom is eliminated.

STEP 11. Using the analyzer, check the ignition failure sensor.

1. Disconnect the ignition failure sensor connector B-01, and connect the test harness special tool MB991658 between the disconnected connectors (All terminals should be connected).

2. Connect the analyzer special patterns pickup to the ignition failure sensor-side connector terminal 2.
3. Crank the engine or run it at idle.

4. Inspect the waveform.
- The waveform should show a normal pattern similar to the illustration.
5. Stop the engine.
If a normal waveform is shown, go to Step 12.
If the waveform does not show a normal pattern, go to Step 13.

STEP 12. Check the harness wire between ignition failure sensor connector B-01 and ECM connector C-37 or PCM connector C-40 .
If the wire between ignition failure sensor connector B-01 and ECM connector C-37 or PCM connector C-40 is damaged, repair it.
If the wire between ignition failure sensor connector B-01 and ECM connector C-37 or PCM connector C-40 is not damaged, repair or replace ignition failure sensor connector B-01. Refer to Harness Connector Inspection >. Then confirm that the malfunction symptom is eliminated.

STEP 13. Check the circuit at ignition failure sensor connector B-01.
1. Disconnect connector B-01 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Measure the voltage between terminal 2 and ground.
- Voltage should be 4 volts or more.
4. Turn the ignition switch "OFF." If less than 4 volts, go to Step 16.
If 4 volts or more, go to Step 14.

STEP 14. Check the ground line at the ignition failure sensor connector B-01.
1. Disconnect connector B-01 and measure at the harness side.
2. Check the continuity between terminal 1 and ground.
- There should be continuity (0 Ohm). If continuity, go to Step 15.
If no continuity, repair the harness wire between ignition failure sensor connector B-01 and ground. Then confirm that the malfunction symptom is eliminated.

STEP 15. Check harness connector B-41 at the ignition failure sensor for damage.
If harness connector B-01 is damaged, repair or replace it. Refer to Harness Connector Inspection >.
If harness connector B-01 is in good condition, replace the ignition failure sensor.
Then confirm that the malfunction symptom is eliminated.

STEP 16. Check the harness wire between ignition failure sensor connector B-01 and ECM connector C-37 or PCM connector C-40 .
If the wire between ignition failure sensor connector B-01 and ECM connector C-37 or PCM connector C-40 is not damaged, go to Step 17.
If the wire between ignition failure sensor connector B-01 and ECM connector C-37 or PCM connector C-40 is damaged, repair it. Then confirm that the malfunction symptom is eliminated.

STEP 17. Check harness connector C-37 at the ECM or harness connector C-40 at the PCM for damage.
If harness connector C-37 or C-40 is damaged, repair or replace it. Refer to Harness Connector Inspection >.
If harness connector C-37 or C-40 is in good condition, replace the ECM or PCM .
Then confirm that the malfunction symptom is eliminated.