Ignition Control Module: Testing and Inspection
Ignition Coil And Power Transistor Circuit:
To test the Power Transistor and Ignition Coil, located on the intake manifold, using an analog type circuit tester, proceed as follows.
POWER TRANSISTOR
Fig. 1 Power Transistor Test (No. 1 & No. 4 Coil Side):
NO. 1 & NO. 4 COIL SIDE
1. Disconnect the power transistor connector.
2. Connect a power supply of 1.5v (one dry cell) between power transistor terminals 2 (+) and 3 (-).
3. Check for continuity between terminals 1 (-) and 3 (+).
Continuity
Should exist
4. Remove power from terminals 1 and 2.
5. Check for continuity between terminals 1 (-) and 3 (+).
Continuity
Should not exist
Fig. 2 Power Transistor Test (No. 2 & No. 3 Coil Side):
NO. 2 & NO. 3 COIL SIDE
1. Disconnect the power transistor connector.
2. Connect a power supply of 1.5v (one dry cell) between power transistor terminals 3 (+) and 5 (-).
3. Check for continuity between terminals 6 (-) and 3 (+).
Continuity
Should exist
4. Remove power from terminals 3 and 5.
5. Check for continuity between terminals 6 (-) and 3 (+).
Continuity
Should not exist
If the Power Transistor fails any of these tests, replace the Power Transistor.
Ignition Coil Primary Circuit Test:
IGNITION COIL
1. Disconnect the ignition coil connector.
2. Using an ohm meter, check the resistance between terminals 2 and 4.
Resistance
0.77 - 0.95 Ohms
3. Using an ohm meter, check the resistance between terminals 1 and 4.
Resistance
0.77 - 0.95 Ohms
Ignition Coil Secondary Circuit Test:
4. Using an ohm meter, check the resistance between secondary terminals for cylinders No. 1 and No. 4.
Resistance
10.3k - 13.9k Ohms Ohms
5. Using an ohm meter, check the resistance between secondary terminals for cylinders No. 2 and No. 3.
Resistance
10.3k - 13.9k Ohms Ohms
Replace the ignition coil if it fails any of these tests.
Power Transistor Control Signal Scope Pattern:
OSCILLOSCOPE TEST
1. Run engine at idle speed.
2. Connect the scope probe to pick-up point #2 (one side at a time) shown in the system schematic diagram and compare each signal to the pattern shown.
If scope pattern is not as depicted in image, continue with the rest of the test procedures before replacing the assembly.
HARNESS TEST
1. Disconnect the ignition coil connector and turn the key to the ON position.
2. Using a Voltmeter, measure the power supply circuit of the ignition coil between the harness connector terminal 4 and ground.
Voltage:
System Voltage.
3. Turn off the ignition and disconnect the ECU connector. Using an Ohmmeter, check for continuity between the coil harness connector terminal 3 and ground.
Continuity:
Should not exist.
4. Using an Ohmmeter, check for continuity between the ECU harness connector terminal 109 and ground.
Continuity:
Should not exist.
5. Disconnect the power transistor connector. Using an Ohmmeter, check for continuity between the coil harness connector terminal 2 and the power transistor harness connector terminal 1.
Continuity:
Should exist.
6. Using an Ohmmeter, check for continuity between the coil harness connector terminal 1 and the power transistor harness connector terminal 5.
Continuity:
Should exist.
7. Using an Ohmmeter, check for continuity between the ECU harness connector terminal 54 and ground.
Continuity:
Should not exist.
8. Using an Ohmmeter, check for continuity between the ECU harness connector terminal 55 and ground.
Continuity:
Should not exist.
9. Using an Ohmmeter, check for continuity between the power transistor harness connector terminal 2 and ground.
Continuity:
Should not exist.
10. Using an Ohmmeter, check for continuity between the power transistor harness connector terminal 4 and ground.
Continuity:
Should not exist.
11. Using an Ohmmeter, check for continuity between the ignition timing check connector terminal and and the ECU harness connector terminal 12.
Continuity:
Should exist.
If any of the previous tests produce unsatisfactory results, the harness will need to be repaired or replaced. Once repairs have been completed, clear the trouble codes and road test the vehicle to confirm that the repair has corrected the problem and the code doesn't return.
If the trouble code returns, it is possible that there is an intermittent failure of the component or the ECU. Check for looseness at all harness junctions and test for an intermittent failure.