Inspection Procedure 32
Ignition Circuit SystemIgnition Circuit:
Connectors:
CIRCUIT OPERATION
- The battery positive voltage is applied on the ignition coil by the ignition switch-IG
- When the PCM turns the power transistor in the PCM "OFF", battery positive voltage is applied on the ignition power transistor (terminals 3), and the ignition power transistor turns "ON".
- When the ignition power transistor turns on, the ignition coil s primary circuit is grounded by the ignition power transistor terminal 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 PCM.
DIAGNOSIS
STEP 1. Check connector B-27 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-27.
1. Disconnect the connector B-27 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal 1 and ground.
- Voltage should be battery positive voltage.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the voltage normal?
YES: Go to Step 5.
NO: Check connector C-04, C-66, C-84 and C-87 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-58 terminal 2 and distributor connector B-27 terminal 1 because of open circuit. Then confirm that the malfunction symptom is eliminated.
STEP 5. Check the continuity at distributor harness side connector B-27.
1. Disconnect the connector B-27 and measure at the harness side.
2. Check for the continuity between terminal 4 and ground.
- Should be less than 2 ohm.
Q: Is the continuity normal?
YES: Go to Step 6.
NO: Repair harness wire between distributor connector B-27 terminal 4 and ground because of open circuit or harness damage. Then confirm that the malfunction symptom is eliminated.
STEP 6. Check connector C-39 at PCM for damage.
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-27 terminal 3 and PCM connector C-39 terminal 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-27 terminal 2 and engine speed detection connector A-12X terminal 1.
Q: Is the harness wire in good condition?
YES: Replace the PCM. Then confirm that the malfunction symptom is eliminated.
NO: Repair it. Then confirm that the malfunction symptom is eliminated.