Inspection Procedure 25: Ignition circuit system










OPERATION



  • The battery voltage is applied to the ignition coil (terminal No. 3) from the ignition switch and is earthed to the vehicle body from the ignition coil (terminal No. 1).
  • A power voltage of 12 V is applied to the ignition coil output terminal (terminal No. 2) from the or engine-A/T-ECU (terminals No. 31, No. 32, No. 35, No. 36, No. 44 and No. 52).

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.

PROBABLE CAUSES



  • 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

DIAGNOSIS PROCEDURE
note
    *1: Ignition coil 1, 3, 5 only
    *2: Ignition coil 2, 4, 6 only

STEP 1. Check spark plug.

Q. Is the check result normal?
Go to Step 2 .
Replace the spark plug.

STEP 2. Connector check: B-07, B-08, B-25, B-29, B-30 and B-33 ignition coil connectors

Q. Are the check results normal?

Go to Step 3 .
Repair or replace the connector.

STEP 3. Check ignition coil itself.

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

Q. Is the check result normal?

Go to Step 4 .
Replace the ignition coil.

STEP 4. Perform voltage measurement at B-07, B-08, B-25, B-29, B-30 and B-33 ignition coil connectors.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: System voltage

Q. Are the check results normal?

Go to Step 6 .
Go to Step 5 .

STEP 5. Connector check: D-309 ignition switch connector

Q. Is the check result normal?


    Check intermediate connectors B-06*2 or B-28*1, D-299, D-403 and D-405, and repair if necessary. If intermediate connectors are normal, check and repair harness between ignition switch connector and ignition coil connector.

  1. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-29 (terminal No. 3) No. 1 ignition coil connector.
  2. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-25 (terminal No. 3) No. 2 ignition coil connector.
  3. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-30 (terminal No. 3) No. 3 ignition coil connector.
  4. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-08 (terminal No. 3) No. 4 ignition coil connector.
  5. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-33 (terminal No. 3) No. 5 ignition coil connector.
  6. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-07 (terminal No. 3) No. 6 ignition coil connector.

  • Check power supply line for open/short circuit.
Repair or replace the connector.

STEP 6. Perform voltage measurement at B-07, B-08, B-25, B-29, B-30 and B-33 ignition coil connectors.

  • Disconnect connector, and measure at harness side.
  • Engine: Cranking
  • Voltage between terminal No. 2 and earth.
OK: 0.3 - 3.0 V

Q. Are the check results normal?

Go to Step 12 .
Go to Step 7 .

STEP 7. Perform voltage measurement at D-214 engine-A/T-ECU connector.

  • Measure engine-A/T-ECU terminal voltage.
  • Disconnect B-07, B-08, B-25, B-29, B-30 and B-33 ignition coil connectors.
  • Engine: Cranking

  1. Voltage between terminal No. 31 and earth (No. 1 Ignition coil).
  2. Voltage between terminal No. 35 and earth (No. 2 Ignition coil).
  3. Voltage between terminal No. 44 and earth (No. 3 Ignition coil).
  4. Voltage between terminal No. 52 and earth (No. 4 Ignition coil).
  5. Voltage between terminal No. 32 and earth (No. 5 Ignition coil).
  6. Voltage between terminal No. 36 and earth (No. 6 Ignition coil).
OK: 0.3 - 3.0 V

Q. Are the check results normal?

Go to Step 8 .
Go to Step 9 .

STEP 8. Connector check: D-214 engine-A/T-ECU connector

Q. Is the check result normal?


    Check and repair harness between ignition coil connector and engine-A/T-ECU connector.

  1. Check and repair harness between B-29 (terminal No. 2) No. 1 ignition coil connector and D-214 (terminal No. 31) engine-A/T-ECU connector.
  2. Check and repair harness between B-25 (terminal No. 2) No. 2 ignition coil connector and D-214 (terminal No. 35) engine-A/T-ECU connector.
  3. Check and repair harness between B-30 (terminal No. 2) No. 3 ignition coil connector and D-214 (terminal No. 44) engine-A/T-ECU connector.
  4. Check and repair harness between B-08 (terminal No. 2) No. 4 ignition coil connector and D-214 (terminal No. 52) engine-A/T-ECU connector.
  5. Check and repair harness between B-33 (terminal No. 2) No. 5 ignition coil connector and D-214 (terminal No. 32) engine-A/T-ECU connector.
  6. Check and repair harness between B-07 (terminal No. 2) No. 6 ignition coil connector and D-214 (terminal No. 36) engine-A/T-ECU connector.

  • Check output line for open circuit.
Repair or replace the connector.

STEP 9. Connector check: D-214 engine-A/T-ECU connector

Q. Is the check result normal?

Go to Step 10 .
Repair or replace the connector.

STEP 10. Check harness between ignition coil connector and engine-A/T-ECU connector.

  1. Check and repair harness between B-29 (terminal No. 2) No. 1 ignition coil connector and D-214 (terminal No. 31) engine-A/T-ECU connector.
  2. Check and repair harness between B-25 (terminal No. 2) No. 2 ignition coil connector and D-214 (terminal No. 35) engine-A/T-ECU connector.
  3. Check and repair harness between B-30 (terminal No. 2) No. 3 ignition coil connector and D-214 (terminal No. 44) engine-A/T-ECU connector.
  4. Check and repair harness between B-08 (terminal No. 2) No. 4 ignition coil connector and D-214 (terminal No. 52) engine-A/T-ECU connector.
  5. Check and repair harness between B-33 (terminal No. 2) No. 5 ignition coil connector and D-214 (terminal No. 32) engine-A/T-ECU connector.
  6. Check and repair harness between B-07 (terminal No. 2) No. 6 ignition coil connector and D-214 (terminal No. 36) engine-A/T-ECU connector.

  • Check output line for short circuit.

Q. Are the check results normal?

Go to Step 11 .
Repair the damaged harness wire.

STEP 11. Check the trouble symptoms.

Q. Does trouble symptom persist?
Replace the engine-A/T-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

STEP 12. Perform resistance measurement at B-07, B-08, B-25, B-29, B-30 and B-33 ignition coil connectors.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 1 and earth.
OK: Continuity (2 Ω or less)

Q. Are the check results normal?

Go to Step 13.

    Check and repair harness between ignition coil connector and body earth.

  1. Check and repair harness between B-29 (terminal No. 1) No. 1 ignition coil connector and body earth
  2. Check and repair harness between B-25 (terminal No. 1) No. 2 ignition coil connector and body earth
  3. Check and repair harness between B-30 (terminal No. 1) No. 3 ignition coil connector and body earth
  4. Check and repair harness between B-08 (terminal No. 1) No. 4 ignition coil connector and body earth
  5. Check and repair harness between B-33 (terminal No. 1) No. 5 ignition coil connector and body earth
  6. Check and repair harness between B-07 (terminal No. 1) No. 6 ignition coil connector and body earth

  • Check earthing line for open circuit and damage.

STEP 13. Check harness between ignition switch connector and ignition coil connector.
note Before checking harness, check intermediate connectors B-06*2 or B-28*1, D-299, D-403 and D-405, and repair if necessary.

  1. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-29 (terminal No. 3) No. 1 ignition coil connector.
  2. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-25 (terminal No. 3) No. 2 ignition coil connector.
  3. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-30 (terminal No. 3) No. 3 ignition coil connector.
  4. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-08 (terminal No. 3) No. 4 ignition coil connector.
  5. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-33 (terminal No. 3) No. 5 ignition coil connector.
  6. Check and repair harness between D-309 (terminal No. 2) ignition switch connector and B-07 (terminal No. 3) No. 6 ignition coil connector.

  • Check power supply line for damage.

Q. Are the check results normal?

Go to Step 14 .
Repair the damaged harness wire.

STEP 14. Check harness between ignition coil connector and engine-A/T-ECU connector.

  1. Check and repair harness between B-29 (terminal No. 2) No. 1 ignition coil connector and D-214 (terminal No. 31) engine-A/T-ECU connector.
  2. Check and repair harness between B-25 (terminal No. 2) No. 2 ignition coil connector and D-214 (terminal No. 35) engine-A/T-ECU connector.
  3. Check and repair harness between B-30 (terminal No. 2) No. 3 ignition coil connector and D-214 (terminal No. 44) engine-A/T-ECU connector.
  4. Check and repair harness between B-08 (terminal No. 2) No. 4 ignition coil connector and D-214 (terminal No. 52) engine-A/T-ECU connector.
  5. Check and repair harness between B-33 (terminal No. 2) No. 5 ignition coil connector and D-214 (terminal No. 32) engine-A/T-ECU connector.
  6. Check and repair harness between B-07 (terminal No. 2) No. 6 ignition coil connector and D-214 (terminal No. 36) engine-A/T-ECU connector.

  • Check output line for damage.

Q. Are the check results normal?

Go to Step 11 .
Repair the damaged harness wire.