Code No. P0350: Ignition Coil Primary Circuit Malfunction <Vehicles for South Africa>


OPERATION



  • The battery voltage is applied to the ignition coil (terminal No. 3) from the engine control relay (terminal No. 2) 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 (terminal No. 2) from the engine-ECU (terminal No. 4, No. 5, No. 20 and No. 21).

FUNCTION



  • When the engine-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-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-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
  • The engine speed is less than approximately 5,000 r/min.
Judgment Criterion
  • The determination signal for the open circuit is continuously output from the confirmation signal circuit for the ignition built in the engine-ECU.

FAIL-SAFE AND BACKUP FUNCTION



  • Fuel is cut for cylinder with ignition coil malfunction.

PROBABLE CAUSES



  • Failed ignition coil
  • Open/short circuit or harness damage in ignition primary circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-21, B-22, B-23 and B-24 ignition coil connectors

Q. Are the check results normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. 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 3 .
Replace the ignition coil.

STEP 3. Perform resistance measurement at B-21, B-22, B-23 and B-24 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 4 .

    Check and repair harness between B-21, B-22, B-23 and B-24 (terminal No. 1) ignition coil connectors and body earth.

    • Check earthing line for open circuit and damage.

STEP 4. Check harness between ignition coil connector and engine-ECU connector.

  1. Check and repair harness between B-21 (terminal No. 2) No. 1 ignition coil connector and B-26 (terminal No. 4) engine-ECU connector
  2. Check and repair harness between B-22 (terminal No. 2) No. 2 ignition coil connector and B-26 (terminal No. 5) engine-ECU connector
  3. Check and repair harness between B-23 (terminal No. 2) No. 3 ignition coil connector and B-26 (terminal No. 20) engine-ECU connector
  4. Check and repair harness between B-24 (terminal No. 2) No. 4 ignition coil connector and B-26 (terminal No. 21) engine-ECU connector

  • Check signal line for open/short circuit and damage.

Q. Are the check results normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).