Mitsubishi Motors Service Manual

2018 / ECLIPSE CROSS / EC - Workshop Manual

13 -FUEL > 13A-DIRECT INJECTION AND MULTIPOINT FUEL INJECTION (DI AND MPI) > TROUBLESHOOTING > SYMPTOM PROCEDURES > IGNITION CIRCUIT SYSTEM

Inspection Procedure 26: Ignition Circuit System

OPERATION

The battery voltage is applied from the engine control relay to the ignition coil and is earthed to the vehicle body via the ignition coil.
A power voltage of 12 V is applied to the ignition coil from the engine-ECU connector terminals CIL1, CIL2, CIL3 and CIL4.

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

DIAGNOSIS PROCEDURE

STEP 1. Visual check of ignition spark.

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.

Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Go to Step 2.

STEP 2. Check spark plug itself.

Spark plug check (Refer to GROUP 16 - Ignition System - On-vehicle Service - Spark Plug Check and Cleaning ).

Is the check result normal?

Go to Step 3.

Replace the spark plug.

STEP 3. Check ignition coil itself.

Ignition coil check (Refer to GROUP 16 - Ignition System - On-vehicle Service - Ignition Coil Check ).

Is the check result normal?

Go to Step 4.

Replace the ignition coil.

STEP 4. Perform voltage measurement at ignition coil connectors.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal power supply line and body earth.

OK: System voltage

Are the check results normal?

Go to Step 5.

Repair the connector(s), or check and repair of open circuit, and short circuit in power supply line between engine control relay connector and ignition coil connector.

STEP 5. Perform resistance measurement at ignition coil connectors.

Disconnect connector, and measure at harness side.
Resistance between terminal earth line and body earth.

OK: Continuity (2 Ω or less)

Are the check results normal?

Go to Step 6.

Repair the connector(s), or check and repair of open circuit, and damage in earth line between ignition coil connectors and body earth.

STEP 6. Check of open circuit, short circuit, and damage between ignition coil connector and engine-ECU connector.

Check and repair in CIL1 line between No. 1 ignition coil connector and engine-ECU connector
Check and repair in CIL2 line between No. 2 ignition coil connector and engine-ECU connector
Check and repair in CIL3 line between No. 3 ignition coil connector and engine-ECU connector
Check and repair in CIL4 line between No. 4 ignition coil connector and engine-ECU connector

Are the check results normal?

Go to Step 7.

Repair the connector(s) or wiring harness.

STEP 7. Check of damage in power supply line between engine control relay connector and ignition coil connectors.

Are the check results normal?

Go to Step 8.

Repair the connector(s) or wiring harness.

STEP 8. Check the trouble symptom.

Does the trouble symptom persist?

Replace the engine-ECU.

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions