Inspection Procedure 30: Ignition Circuit System

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. 31, No. 32, No. 35 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 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

DIAGNOSIS PROCEDURE

NOTE:

^*1 : L.H. drive vehicle

^*2 : R.H. drive vehicle

STEP 1. Check spark plug.

Q: Is the check result normal?

YES: Go to Step 2

.
NO: Replace spark plug.

STEP 2. Connector check: B-110, B-111, B-121 and B-120 ignition coil connectors

Q: Is the check result normal?

YES: Go to Step 3

.
NO: Repair.

STEP 3. Check ignition coil itself.

Check ignition coil itself (Refer to GROUP 16 - Ignition System - On-vehicle Service - Ignition coil check <4G69>).

Q: Is the check result normal?

YES: Go to Step 4

.
NO: Replace ignition coil.

STEP 4. Perform voltage measurement at B-110, B-111, B-121 and B-120 ignition coil connectors.

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 6

.
NO: Go to Step 5

STEP 5. Connector check: C-303 ignition switch connector

Q: Is the check result normal?

YES:

Check intermediate connectors A-14^*1 , C-116^*1 , C-126^*2 , C-203 and C-205, and repair if necessary. If intermediate connectors are normal, check and repair harness between ignition switch connector and ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-110 (terminal No. 1) No. 1 ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-111 (terminal No. 1) No. 2 ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-121 (terminal No. 1) No. 3 ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-120 (terminal No. 1) No. 4 ignition coil connector

Check power supply line for open/short circuit.

NO: Repair.

STEP 6. Perform voltage measurement at B-110, B-111, B-121 and B-120 ignition coil connectors.

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 12

.
NO: Go to Step 7

STEP 7. Perform voltage measurement at C-135 engine-A/T-ECU connector.

Measure engine-A/T-ECU terminal voltage.

Disconnect B-110, B-111, B-121 and B-120 ignition coil connectors.

Engine: Cranking

Voltage between terminal No. 31 and earth (No. 1 Ignition coil).

Voltage between terminal No. 32 and earth (No. 2 Ignition coil).

Voltage between terminal No. 35 and earth (No. 3 Ignition coil).

Voltage between terminal No. 52 and earth (No. 4 Ignition coil).

OK: 0.5 - 4.0 V

Q: Is the check result normal?

YES: Go to Step 8

.
NO: Go to Step 9

STEP 8. Connector check: C-135 engine-A/T-ECU connector

Q: Is the check result normal?

YES:

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

Check and repair harness between B-110 (terminal No. 3) No. 1 ignition coil connector and C-135 (terminal No. 31) engine-A/T-ECU connector.

Check and repair harness between B-111 (terminal No. 3) No. 2 ignition coil connector and C-135 (terminal No. 32) engine-A/T-ECU connector.

Check and repair harness between B-121 (terminal No. 3) No. 3 ignition coil connector and C-135 (terminal No. 35) engine-A/T-ECU connector.

Check and repair harness between B-120 (terminal No. 3) No. 4 ignition coil connector and C-135 (terminal No. 52) engine-A/T-ECU connector.

Check output line for open circuit.

NO: Repair.

STEP 9. Connector check: C-135 engine-A/T-ECU connector

Q: Is the check result normal?

YES: Go to Step 10

.
NO: Repair.

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

Check and repair harness between B-110 (terminal No. 3) No. 1 ignition coil connector and C-135 (terminal No. 31) engine-A/T-ECU connector.

Check and repair harness between B-111 (terminal No. 3) No. 2 ignition coil connector and C-135 (terminal No. 32) engine-A/T-ECU connector.

Check and repair harness between B-121 (terminal No. 3) No. 3 ignition coil connector and C-135 (terminal No. 35) engine-A/T-ECU connector.

Check and repair harness between B-120 (terminal No. 3) No. 4 ignition coil connector and C-135 (terminal No. 52) engine-A/T-ECU connector.

Check output line for short circuit.

Q: Is the check result normal?

YES: Go to Step 11

.
NO: Repair.

STEP 11. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES: Replace engine-A/T-ECU.
NO: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points

STEP 12. Perform resistance measurement at B-110, B-111, B-121 and B-120 ignition coil connectors.

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 13

.
NO:

Check and repair harness between ignition coil connector and body earth

Check and repair harness between B-110 (terminal No. 2) No. 1 ignition coil connector and body earth

Check and repair harness between B-111 (terminal No. 2) No. 2 ignition coil connector and body earth

Check and repair harness between B-121 (terminal No. 2) No. 3 ignition coil connector and body earth

Check and repair harness between B-120 (terminal No. 2) No. 4 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.

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-110 (terminal No. 1) No. 1 ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-111 (terminal No. 1) No. 2 ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-121 (terminal No. 1) No. 3 ignition coil connector

Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-120 (terminal No. 1) No. 4 ignition coil connector

NOTE: Before checking harness, check intermediate connectors A-14^*1 , C-116^*1 , C-126^*2 , 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 14

.
NO: Repair.

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

Check and repair harness between B-110 (terminal No. 3) No. 1 ignition coil connector and C-135 (terminal No. 31) engine-A/T-ECU connector.

Check and repair harness between B-111 (terminal No. 3) No. 2 ignition coil connector and C-135 (terminal No. 32) engine-A/T-ECU connector.

Check and repair harness between B-121 (terminal No. 3) No. 3 ignition coil connector and C-135 (terminal No. 35) engine-A/T-ECU connector.

Check and repair harness between B-120 (terminal No. 3) No. 4 ignition coil connector and C-135 (terminal No. 52) engine-A/T-ECU connector.

Check output line for damage.

Q: Is the check result normal?

YES: Go to Step 11

.
NO: Repair.


Inspection Procedure 30: Ignition Circuit System

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. 31, No. 32, No. 35 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 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
	DIAGNOSIS PROCEDURE NOTE: ^1 : L.H. drive vehicle ^2 : R.H. drive vehicle

	STEP 1. Check spark plug. Q: Is the check result normal? YES: Go to Step 2 . NO: Replace spark plug.
	STEP 2. Connector check: B-110, B-111, B-121 and B-120 ignition coil connectors
	Q: Is the check result normal? YES: Go to Step 3 . NO: Repair.
	STEP 3. Check ignition coil itself. Check ignition coil itself (Refer to GROUP 16 - Ignition System - On-vehicle Service - Ignition coil check <4G69>). Q: Is the check result normal? YES: Go to Step 4 . NO: Replace ignition coil.
	STEP 4. Perform voltage measurement at B-110, B-111, B-121 and B-120 ignition coil connectors.
	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 6 . NO: Go to Step 5 .
	STEP 5. Connector check: C-303 ignition switch connector
	Q: Is the check result normal? YES: Check intermediate connectors A-14^1 , C-116^1 , C-126^*2 , C-203 and C-205, and repair if necessary. If intermediate connectors are normal, check and repair harness between ignition switch connector and ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-110 (terminal No. 1) No. 1 ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-111 (terminal No. 1) No. 2 ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-121 (terminal No. 1) No. 3 ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-120 (terminal No. 1) No. 4 ignition coil connector Check power supply line for open/short circuit. NO: Repair.
	STEP 6. Perform voltage measurement at B-110, B-111, B-121 and B-120 ignition coil connectors.
	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 12 . NO: Go to Step 7 .
	STEP 7. Perform voltage measurement at C-135 engine-A/T-ECU connector.
	Measure engine-A/T-ECU terminal voltage. Disconnect B-110, B-111, B-121 and B-120 ignition coil connectors. Engine: Cranking Voltage between terminal No. 31 and earth (No. 1 Ignition coil). Voltage between terminal No. 32 and earth (No. 2 Ignition coil). Voltage between terminal No. 35 and earth (No. 3 Ignition coil). Voltage between terminal No. 52 and earth (No. 4 Ignition coil). OK: 0.5 - 4.0 V Q: Is the check result normal? YES: Go to Step 8 . NO: Go to Step 9 .
	STEP 8. Connector check: C-135 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Check and repair harness between ignition coil connector and engine-A/T-ECU connector Check and repair harness between B-110 (terminal No. 3) No. 1 ignition coil connector and C-135 (terminal No. 31) engine-A/T-ECU connector. Check and repair harness between B-111 (terminal No. 3) No. 2 ignition coil connector and C-135 (terminal No. 32) engine-A/T-ECU connector. Check and repair harness between B-121 (terminal No. 3) No. 3 ignition coil connector and C-135 (terminal No. 35) engine-A/T-ECU connector. Check and repair harness between B-120 (terminal No. 3) No. 4 ignition coil connector and C-135 (terminal No. 52) engine-A/T-ECU connector. Check output line for open circuit. NO: Repair.
	STEP 9. Connector check: C-135 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Go to Step 10 . NO: Repair.
	STEP 10. Check harness between ignition coil connector and engine-A/T-ECU connector.
	Check and repair harness between B-110 (terminal No. 3) No. 1 ignition coil connector and C-135 (terminal No. 31) engine-A/T-ECU connector. Check and repair harness between B-111 (terminal No. 3) No. 2 ignition coil connector and C-135 (terminal No. 32) engine-A/T-ECU connector. Check and repair harness between B-121 (terminal No. 3) No. 3 ignition coil connector and C-135 (terminal No. 35) engine-A/T-ECU connector. Check and repair harness between B-120 (terminal No. 3) No. 4 ignition coil connector and C-135 (terminal No. 52) engine-A/T-ECU connector. Check output line for short circuit. Q: Is the check result normal? YES: Go to Step 11 . NO: Repair.
	STEP 11. Check the trouble symptoms. Q: Does trouble symptom persist? YES: Replace engine-A/T-ECU. NO: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).
	STEP 12. Perform resistance measurement at B-110, B-111, B-121 and B-120 ignition coil connectors.
	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 13. NO: Check and repair harness between ignition coil connector and body earth Check and repair harness between B-110 (terminal No. 2) No. 1 ignition coil connector and body earth Check and repair harness between B-111 (terminal No. 2) No. 2 ignition coil connector and body earth Check and repair harness between B-121 (terminal No. 2) No. 3 ignition coil connector and body earth Check and repair harness between B-120 (terminal No. 2) No. 4 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.
	Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-110 (terminal No. 1) No. 1 ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-111 (terminal No. 1) No. 2 ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-121 (terminal No. 1) No. 3 ignition coil connector Check and repair harness between C-303 (terminal No. 2) ignition switch connector and B-120 (terminal No. 1) No. 4 ignition coil connector NOTE: Before checking harness, check intermediate connectors A-14^1 , C-116^1 , C-126^*2 , 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 14 . NO: Repair.
	STEP 14. Check harness between ignition coil connector and engine-A/T-ECU connector.
	Check and repair harness between B-110 (terminal No. 3) No. 1 ignition coil connector and C-135 (terminal No. 31) engine-A/T-ECU connector. Check and repair harness between B-111 (terminal No. 3) No. 2 ignition coil connector and C-135 (terminal No. 32) engine-A/T-ECU connector. Check and repair harness between B-121 (terminal No. 3) No. 3 ignition coil connector and C-135 (terminal No. 35) engine-A/T-ECU connector. Check and repair harness between B-120 (terminal No. 3) No. 4 ignition coil connector and C-135 (terminal No. 52) engine-A/T-ECU connector. Check output line for damage. Q: Is the check result normal? YES: Go to Step 11 . NO: Repair.