Inspection Procedure 33
Ignition Circuit SystemIgnition Circuit Part 1:
Ignition Circuit Part 2:
CIRCUIT OPERATION
- The battery positive voltage is applied on the ignition coil by the ignition switch-IG.
- When the ECM
- When the ignition power transistor turns on, the ignition coil's primary circuit is grounded by the ignition power transistor terminal No. 4. Then the primary current flows to the ignition coil.
TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the ignition coil.
- Malfunction of the ignition power transistor.
- Improper connector contact, open circuit or short-circuited harness wire.
- Malfunction of the ECM
DIAGNOSIS
STEP 1. Check connector B-22 at distributor for damage.
Q: Is the connector in good condition?
YES: Go to Step 2.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.
STEP 2. Check the ignition coil.
Refer to Ignition System - On-vehicle service - Ignition coil check.
Q: Are there any abnormalities?
YES: Go to Step 3.
NO: Repair the ignition coil. Then confirm that the malfunction symptom is eliminated.
STEP 3. Check the ignition power transistor.
Refer to Ignition System - On-vehicle service - Power transistor check.
Q: Are there any abnormalities?
YES: Go to Step 4.
NO: Repair the ignition power transistor. Then confirm that the malfunction symptom is eliminated.
STEP 4. Check the power supply voltage at distributor connector B-22.
1. Disconnect the connector B-22 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 1 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 5.
NO: Check connector C-07, C-89, C-108 and C-111 at intermediate connectors for damage, and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connectors are in good condition, repair harness wire between ignition switch connector C-87 terminal 2 and distributor connector B-22 (terminal No. 1) because of open circuit. Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the continuity at distributor harness side connector B-22.
1. Disconnect the connector B-22 and measure at the harness side.
2. Check for the continuity between terminal No. 4 and ground.
- Should be less than 2 Ohms.
Q: Is the continuity normal?
YES: Go to Step 6.
NO: Repair harness wire between distributor connector B-22 (terminal No. 4) and ground because of open circuit or harness damage. Then confirm that the malfunction symptom is eliminated.
STEP 6. Check connector C-51 at ECM
Q: Is the connector in good condition?
YES: Go to Step 7.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then confirm that the malfunction symptom is eliminated.
STEP 7. Check for open circuit between distributor connector B-22 (terminal No. 3) and ECM connector C-51 (terminal No. 11)
Q: Is the harness wire in good condition?
YES: Go to Step 8.
NO: Repair it. Then confirm that the malfunction symptom is eliminated.
STEP 8. Check for open circuit between distributor connector B-22 (terminal No. 2) and engine speed detection connector A-12X (terminal No. 1).
Q: Is the harness wire in good condition?
YES: Replace the ECM or PCM. Then confirm that the malfunction symptom is eliminated.
NO: Repair it. Then confirm that the malfunction symptom is eliminated.