Inspection Procedure 32

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




WIRING DIAGRAM




CONNECTORS

DIAGNOSIS




STEP 1. Check the power supply line at the distributor connector B-27.
1. Disconnect connector B-27 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Connect terminal 1 and ground via a 20-Ohm resistor. Measure the current at this time.
- The current should be 0.5 ampere or more.
4. Turn the ignition switch "OFF."
If within specifications, go to Step 2.
If not within specifications, repair the harness wire and connector between the ignition coil and the ignition switch. Refer to Harness Connector Inspection >. Then confirm that the malfunction symptom is eliminated.




STEP 2. Check the ground line at the distributor connector B-27.
1. Disconnect connector B-27 and measure at the harness side.
2. Check for the continuity between terminal 4 and ground.
- There should be continuity (0 Ohm).
If continuity, go to Step 3.
If no continuity, repair the harness wire between the distributor connector B-27 and ground. Then confirm that the malfunction symptom is eliminated.

STEP 3. Check the ignition coil.
Refer to Ignition System.
If correct, go to Step 4.
If incorrect, replace the distributor assembly. Then confirm that the malfunction symptom is eliminated.

STEP 4. Check the ignition power transistor.
Refer to Ignition System.
If correct, go to Step 5.
If incorrect, replace the distributor assembly. Then confirm that the malfunction symptom is eliminated.




STEP 5. Check the circuit at the distributor connector B-27.
1. Disconnect connector B-27 and measure at the harness side.
2. Crank the engine.
3. Measure voltage between terminal 3 and ground.
- Voltage should be between 2 and 7 volts.
If not within specifications, go to Step 6. If within specifications, go to Step 8.







STEP 6. Check the harness wire between the distributor connector B-27 (terminal 3) and the PCM connector C-39 (terminal 11).
If the wire between distributor connectors B-27 (terminal 3) and PCM connector C-39 (terminal 11) is not damaged, go to Step 7.
If the wire between distributor connectors B-27 (terminal 3) and PCM connector C-39 (terminal 11) is damaged, repair it. Then check that the malfunction is eliminated.




STEP 7. Check the harness connector C-39 at the PCM for damage.
If the harness connector C-39 is damaged, repair or replace it. Refer to Harness Connector Inspection >. If harness connector C-39 is normal, replace the PCM. Then check the malfunction is eliminated.







STEP 8. Check the harness wire between the distributor connector B-27 (terminal 2) and the PCM connector C-40 (terminal 43).
If the wire between distributor connectors B-27 (terminal 2) and PCM connector C-40 (terminal 43) is not damaged, go to Step g.
If the wire between distributor connectors B-27 (terminal 2) and PCM connector C-40 (terminal 43) is damaged, repair it. Then check that the malfunction is eliminated.







STEP 9. Check the harness connector B-27 at the distributor and the harness connector C-40 at the PCM for damage.
If the harness connector B-27 and C-40 are damaged, repair or replace them. Refer to Harness Connector Inspection >.
If the harness connectors B-27 and C-40 are in good condition, replace the PCM.
Then check the malfunction is eliminated.