Inspection Procedure 22: Ignition Circuit System
OPERATION
- The battery voltage is applied from the engine control relay connector terminal to the ignition coil connector terminal and is earthed to the vehicle body via the ignition coil connector terminal.
- A power voltage of 12 V is applied to the ignition coil connector terminal from the engine-ECU connector terminals CIL1, CIL2, CIL3, CIL4, CIL5 and CIL6.
FUNCTION
- When the engine-ECU turn the power transistor in the unit to OFF, the battery voltage is applied to the power transistor in the ignition coil, resulting that the power transistor is ON. And, when the engine-ECU turns the power transistor in the unit to ON, the power transistor in the ignition coil will be turned OFF.
- When the power transistor in the ignition coil is turned to ON with any signal from the engine-ECU, the primary voltage will be applied through the ignition coil. When the power transistor in the ignition coil is turned OFF, the primary current is blocked and high voltage is generated in the secondary coil.
PROBABLE CAUSES
- Failed spark plug
- Failed ignition coil
- Open/short circuit or harness damage in ignition system circuit or loose connector contact
- Failed engine-ECU
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STEP 1. Visual check of ignition spark.
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- Remove the spark plug and install it to the ignition coil.
- Connect the ignition coil connector.
- Disconnect all injector connectors.
- At the engine start, check each spark plug produces a spark.
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Q.
Is the check result normal?
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 Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions  ).
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 Go to Step 2.
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STEP 2. Check spark plug.
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- Check spark plug (Refer to GROUP 16 - Ignition System - On-vehicle Service - Spark Plug Check and Cleaning ).
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Q.
Is the check result normal?
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Go to Step 3.
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Replace the spark plug.
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STEP 3. Check ignition coil itself.
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- Check ignition coil itself (Refer to GROUP 16 - Ignition System - On-vehicle Service - Ignition Coil Check ).
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Q.
Is the check result normal?
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Go to Step 4.
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Replace the ignition coil.
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STEP 4. Voltage measurement at No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector (power supply line).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Check the voltage between the No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector (power supply line) and body earth.
OK: System voltage
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Q.
Are the check results normal?
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Go to Step 5.
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Repair or replace the connector(s), or check and repair the harness of short to earth, and open circuit in power supply line between engine control relay connector and No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector.
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STEP 5. Resistance measurement at No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector (body earth line).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Measure the resistance between the No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector (body earth line) and body earth.
OK: Continuity (2 Ω or less)
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Q.
Are the check results normal?
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Go to Step 6.
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Repair or replace the connector(s), or check and repair the harness of open circuit and damage in body earth line between No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector and body earth.
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STEP 6. Check of short to earth, open circuit and damage in CIL1, CIL2, CIL3, CIL4, CIL5, CIL6 line between No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector and engine-ECU connector.
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Q.
Are the check results normal?
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Go to Step 7.
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Repair the connector(s) or wiring harness.
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STEP 7. Check of harness damage in CIL1, CIL2, CIL3, CIL4, CIL5, CIL6 line between engine control relay connector and No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 ignition coil connector.
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Q.
Are the check results normal?
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Go to Step 8.
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Repair the connector(s) or wiring harness.
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STEP 8. Check the trouble symptom.
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Q.
Does the trouble symptom persist?
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Replace the engine-ECU.
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
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