Ignition Coil and Ignition Power Transistor
IGNITION COIL AND IGNITION POWER TRANSISTOR
OPERATION
- When the ignition power transistor unit A is turned on by the signal from the engine control module, primary current flows to the ignition coil A. When the ignition power transistor unit A is turned off, the primary current is shut off and a high voltage is induced in the secondary coil A, causing the ignition plugs of No. 1 and No.4 cylinders to spark. When the ignition power transistor unit B is turned off, the ignition plugs of No.2 and No.5 cylinders spark. In addition, when the ignition power transistor unit C is turned off, the ignition plugs of No.3 and No.6 cylinders spark.
- When the engine control module turns off the transistor in the module, the battery voltage in the module is applied to the ignition power transistor unit to turn it on. When the engine control module turns on the transistor in the module, the ignition power transistor unit is turned off.
INSPECTION
Using Scan Tool
<Ignition timing adjustment mode>
Using Oscilloscope
1. Primary signal of ignition coil
1. Run the engine at an idle speed.
2. Connect the probe to oscilloscope pick-up point 1 as shown in the circuit diagram, and check the primary signal of the ignition coil.
2. Control signal of ignition power transistor
Connect the probe to oscilloscope pick-up point 2 as shown in the circuit diagram, and check the control signal of the ignition power transistor.
HARNESS INSPECTION
Measure the power supply voltage of the ignition coil.
- Connector: Disconnected
- Ignition switch: ON
Voltage (V): Battery positive voltage
OK: GO TO STEP 2
NG: Repair the harness. (A3 - Ignition switch)
Measure the power supply voltage of the ignition coil.
- connector: Disconnected
- Ignition switch: ON
OK: GO TO STEP 3
NG: Repair the harness. (B6 - Ignition Switch)
Check for open-circuit or short circuit to ground between engine control unit and the ignition power transistor.
- Engine control module connector: Disconnected
- Ignition power transistor connector: Disconnected
OK: GO TO STEP 4
NG: Repair the harness (B5 - 45)
Check for an open-circuit, or a short-circuit to ground between the ignition power transistor and the ignition coil.
- Ignition coil connector: Disconnected
- Ignition power transistor connector: Disconnected
OK: GO TO STEP 5
NG: Repair the harness. (A2 - B13) (A1 - B12) (A4 - B11)
Check for continuity of the ground circuit.
- Connector: Disconnected
OK: GO TO STEP 6
NG: Repair the harness. (B4 - Ground)
Measure the voltage of the control signal circuit of the ignition power transistor.
- Connector: Disconnected
- Ignition switch: START
Voltage (V): 0.5 - 4.0
OK: GO TO STEP 7
NG: Repair the harness. (B3 - 11) (B2 - 12) (B1 - 13)
Measure the voltage of the ignition timing adjustment terminal.
- Ignition switch: ON
Voltage (V): 4.0 - 5.2
OK: STOP
NG: Repair the harness. (C1 -23)
IGNITION COIL AND IGNITION TRANSISTOR CHECK
Refer to Ignition System.