OPERATION
- The battery voltage is applied to the ignition coil (terminal No. 1) from the ignition switch and is earthed to the vehicle body from the ignition coil (terminal No. 2).
- A power voltage of 12 V is applied to the ignition coil output terminal (terminal No. 3) from the engine-A/T-ECU (terminal No. 11 and No. 12).
FUNCTION
- When the engine-A/T-ECU makes the power transistor in the unit be in "OFF" position, the battery voltage in the unit is applied to the power transistor unit, and that makes the power transistor unit be in "ON" position. The engine-A/T-ECU makes the power transistor in the unit be in "ON", and that makes the power transistor unit be in "OFF" position.
- In response to the signal from the engine-A/T-ECU, the power transistor unit is in "ON" position. The primary current is going to the ignition coil. When the power transistor unit is in "OFF" position, the primary current is interrupted and high voltage is generated in the secondary coil.
TROUBLE JUDGMENT
Check Condition
- Engine speed 500 - 4,000 r/min <SOHC>.
- Engine speed 1,500 - 3,500 r/min <DOHC>.
- Volumetric efficiency 30 - 60% <SOHC>.
- Volumetric efficiency 40 - 80% <DOHC>.
- Engine not in cranking state.
Judgment Criterion
- Crank angle sensor detects abnormal rotation caused by misfire (one failed coil of the two coils) <SOHC>.
- When an open circuit decision signal is continuously output from the ignition signal check circuit built into the engine-A/T-ECU <DOHC>.
PROBABLE CAUSE
- Failed ignition coil
- Failed spark plug
- Failed spark plug cable
- Open/short circuit in ignition primary circuit or loose connector contact
- Failed engine-A/T-ECU
)
Q: Is the check result normal?
YES:
Go to Step 4 
.NO: Repair.
- Disconnect connector, and measure at harness side.
- Ignition switch: ON
- Voltage between terminal No. 1 and earth.
OK: System voltage
Q: Is the check result normal?
YES:
Go to Step 7 .NO: Go to Step 6
.)
Q: Is the check result normal?
YES:
- Check intermediate connectors C-203, C-205, C-116 and C-126 and repair if necessary. If intermediate connectors are normal, check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-111 (terminal No. 1) ignition coil connector, also between C-303 (terminal No. 2) ignition switch connector and B-110 (terminal No. 1) ignition coil connector.
- Check power supply line for open/short circuit.
- Disconnect connector, and measure at harness side.
- Engine: Cranking
- Voltage between terminal No. 3 and earth.
OK: 0.5 -
4.0 V
Q: Is the check result normal?
YES:
Go to Step 13 .NO: Go to Step 8
.)
- Measure engine-A/T-ECU terminal voltage.
- Disconnect B-111 and B-110 ignition coil connectors.
- Engine: Cranking
- Voltage between terminal No. 11 and earth, also between terminal No. 12 and earth.
OK: 0.5 -
4.0 V
Q: Is the check result normal?
YES:
Go to Step 9 .NO: Go to Step 10
.
Q: Is the check result normal?
YES:
- Check and repair harness between B-111 (terminal No. 3) ignition coil connector and C-112 (terminal No. 11) engine-A/T-ECU connector, also between B-110 (terminal No. 3) ignition coil connector and C-112 (terminal No. 12) engine-A/T-ECU connector.
- Check output line for open circuit.
Q: Is the check result normal?
YES:
Go to Step 11 .NO: Repair.
- Check output line for short circuit.
Q: Is the check result normal?
YES:
Go to Step 12 .NO: Repair.
- Disconnect connector, and measure at harness side.
- Resistance between terminal No. 2 and earth.
OK: 2 Ω
or less
Q: Is the check result normal?
YES:
Go to Step 14 .NO:
- Check and repair harness between B-111 (terminal No. 2) ignition coil connector and body earth, also between B-110 (terminal No. 2) ignition coil connector and body earth.
- Check earthing line for open circuit and damage.
NOTE: Before checking harness, check intermediate connectors C-126, C-203 and C-205, and repair
if necessary.
- Check power supply line for damage.
Q: Is the check result normal?
YES:
Go to Step 15 .NO: Repair.
- Check output line for damage.
Q: Is the check result normal?
YES:
Go to Step 12 .NO: Repair.