Ignition Coil Operation Test
Ignition Coil Operation Test
For a complete wiring diagram, refer to.
Test Step 1 - Ignition Coil Wiring and Connectors
• Diagnose and resolve any ignition coil, CMP sensor or CKP sensor DTCs before proceeding with this test.
• Turn the ignition off.
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ignition coil for the cylinder being tested and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• If the vehicle is not equipped with the coil on plug ignition system, check the resistance of the ignition wires before checking the cylinder with a spark tester. The resistance should be less than 10k ohms.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
No
• Go to Test Step 2
Test Step 2 - Ignition Coil Operation
• Inspect the ignition coil for damage, carbon tracking on the coil or a damaged spark plug insulator boot. If a problem is found, replace the ignition coil.
• Some coils must have a spark tester installed on both sides of the coil during the following test. During the test, each side of the coil should output a crisp blue spark that is able to jump the gap of the spark tester.
• On some engines, it may be necessary to remove the upper intake manifold to access the ignition coils. Once the ignition coil has been removed, the intake must be installed in order to crank the engine. Move the ignition coil harness connector through the slots in the upper intake and then connect the coil to the harness connector. Secure the upper intake to the lower intake.
• Turn the ignition off.
• If the vehicle is equipped with coil on plug ignition system, remove the ignition coil for the cylinder being tested.
• Disconnect the fuel injector harness connector for the cylinder being tested.
• For coil on plug ignition systems, install a spark tester on the ignition coil, otherwise install the spark tester to the ignition wire.
• While cranking the engine observe the spark from the spark tester.
• A crisp blue spark that jumps the gap of the spark tester should be generated.
Is good spark present?
Yes
• Go to Test Step 7
No
• Go to Test Step 3
Test Step 3 - Main/ASD Relay Output Circuit Open or High Resistance
• Turn the ignition off.
• Disconnect the ignition coil harness connector.
• Turn the ignition on.
• With the scan tool, actuate the main/ASD relay.
• Using a 12 volt test lamp connected to ground, check the main/ASD relay output circuit in the ignition coil harness connector.
• The test lamp should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.
Is the test lamp brightly illuminated during the actuation?
Yes
• Go to Test Step 4
No
• Repair the main/ASD relay output circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
Test Step 4 - Ignition Coil
When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
• Using a test lamp connected to 12 volts, check the ignition coil control circuit for the cylinder being tested in the ignition coil harness connector.
• Crank the engine for 5 seconds.
• The test lamp should blink each time the circuit is activated by the PCM.
Does the test lamp blink each time the circuit is activated by the PCM?
Yes
• Replace the ignition coil.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
No
• Go to Test Step 5
Test Step 5 - Ignition Coil Control Circuit Open or High Resistance
Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals, resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
• Measure the resistance of the ignition coil control circuit for the cylinder being tested between the ignition coil harness connector and the appropriate terminal of special tool #8815.
Is the resistance less than 5.0 ohms?
Yes
• Go to Test Step 6
No
• Repair the ignition coil control circuit for an open or high resistance.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
Test Step 6 - Powertrain Control Module
• Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ignition coil for the cylinder being tested and the PCM.
• Look for any chafed, pierced, pinched, or partially broken wires.
• Look for broken, bent, pushed out or corroded terminals.
• Refer to any TSBs that may apply.
Were any problems found?
Yes
• Repair as necessary.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
No
• Replace and program the PCM.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
Test Step 7 - Spark Plugs
• Turn the ignition off.
• Remove the spark plug.
Inspect the spark plug for any of the following conditions:
• Cracks or damage.
• Carbon tracking.
• Foreign material.
• Gap not within specification.
• Loose or broken electrode.
• Lightly tap the bottom of the spark plug on a solid surface. The electrode in the spark plug should not move.
Were any problems found?
Yes
• Replace the spark plug.
• Perform the PCM Verification Test. Refer to => [ PCM Verification Test ] PCM Verification Test.
No
• Test Complete.