Circuit Description
The Secondary Ignition Diagnosis tests the spark plugs, ignition coils, and ignition control modules. The PCM causes a spark to occur by grounding the IC circuit, which signals the ignition control module to trigger the ignition coil and fire the spark plug. The PCM controls the sequencing and timing of the spark based on the crankshaft and camshaft sensors input.
Diagnostic Aids
When servicing the ignition system components, use the following recommended procedures:
| • | If a boot remains attached to a coil or spark plug, twist the boot prior to removal. |
| • | Inspect the boot for a missing or damaged internal spring. |
| • | Do not re-install any component that has visible signs of damage. |
| • | Install the boots onto the coils (until bottomed out). Then install the assembly onto the spark plugs. If this is not possible due to space limitations, start the boots onto the spark plugs and then install the coil assembly as straight down onto the plugs as possible. |
| • | Ensure the boots are installed right side up. |
| • | Lift the module beauty cover at the end opposite the module to remove. |
| • | Repair a torn perimeter seal with RTV sealant. |
| • | Adhere to the torque specifications when installing the coil cassette to the cam cover and the ignition module to the coil cassette. |
A suspected ignition system misfire may actually be a condition other than the secondary ignition system. Verify proper operation of the following items:
| • | Fuel System |
| - | . |
| • | Engine Mechanical |
| Test for base engine conditions that could produce an engine misfire. Refer to Base Engine Misfire Diagnosis in Engine Mechanical 4.6L. |
If the misfire is not present while operating the engine with the J 36012 spark plug jumper wires in place, and the misfire is present while the boots are installed, replace the affected boot.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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An ignition coil, boots or spark plugs may misfire only when moisture is present. Although difficult to test on this engine, selectively wetting down parts of the system and monitoring for misfire, may isolate an intermittent condition. If moisture is present in the spark plug/ignition coil cavity of the cam cover, inspect the perimeter seal for damage. Repair tears in the perimeter seal with RTV sealant.
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The J 26792 spark tester (ST 125) places a higher load on the secondary ignition than a normal spark plug.
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Use the correct adaptor harness when connecting the Ignition Module Tester. Using an adaptor harness for a different engine application will result in incorrect tool operation.
The green Power LED should come on any time the ignition module tester is connected and the ignition switch is in the run position. This LED indicates that the J 43298 is receiving adequate power and ground to perform the test. The Test button is used as an LED check for the four red LEDs. To use this function, connect the tool, turn the ignition switch to run, then momentarily press the Test button. All four red LEDs should come on brightly. Then crank the vehicle. If the four red LEDs flash, this confirms proper operation of the primary ignition system (PCM, wiring, connections, and ICM). The Ignition Module Tester may get hot during actual testing. This is because it is attempting to simulate the load of the ignition coils primary windings.
If the LEDs flash, the module output drivers are operating. If one or more LEDs are inoperative, and no individual IC Circuit (351-358), or IC Circuit Group (1359 and/or 1360) DTCs are set, replace the module.
Step | Action | Value(s) | Yes | No | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | ||||||||||||||||
2 |
Important: This table assumes that there are no injector circuit malfunctions or mechanical malfunctions. If you were not sent here from DTC P0300, refer to DTC P0300 Engine Misfire Detected before proceeding with this table. Are any of the following DTCs set?
| -- | ||||||||||||||||
3 |
Do any of the cylinders indicate an excessive amount of misfire? | -- | Go to Intermittent Conditions | |||||||||||||||
4 | Is the misfire affecting one entire bank of the engine? | -- | ||||||||||||||||
5 |
Is the frequency within the specified range? | 1-2 Hz | ||||||||||||||||
Did you find and correct the condition? | -- | System OK | ||||||||||||||||
Does a spark jump the tester gap and is the spark consistent? | -- | |||||||||||||||||
8 |
Important: If the spark plug shows signs of oil or coolant fouling, refer to Base Engine Misfire Diagnosis in Engine Mechanical. Remove the spark plug for the affected cylinder. Refer to Spark Plug Replacement in Engine Electrical. Does the spark plug show signs of oil or coolant entering the combustion chamber? | -- | ||||||||||||||||
9 | Inspect the spark plug for the following conditions:
Did you find a condition with the spark plug? | -- | ||||||||||||||||
10 |
Did the misfire move with the spark plug? | -- | Go to Base Engine Misfire Diagnosis in Engine Mechanical | |||||||||||||||
11 |
Does the DMM display continuity? | -- | ||||||||||||||||
12 |
Does the test lamp illuminate? | -- | ||||||||||||||||
13 | Probe the ignition control module ground circuit with a test lamp connected to B+. Does the test lamp illuminate? | -- | ||||||||||||||||
Important: Ensure that the green power LED is illuminated before proceeding. Do four LEDs flash ON and OFF as the engine is cranked? | -- | |||||||||||||||||
15 | Repair the ignition control module B+ supply circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- | ||||||||||||||
16 | Repair the ignition control module ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | System OK | -- | ||||||||||||||
17 | Repair the ignition control circuit for an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | System OK | -- | ||||||||||||||
18 | Replace the spark plug. Refer to Spark Plug Replacement in Engine Electrical. Is the action complete? | -- | System OK | -- | ||||||||||||||
19 | Inspect for poor connections between the ignition control module and the coil assembly. Refer to Connector Repairs in Wiring Systems. If the condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | System OK | |||||||||||||||
20 | Replace the affected coil assembly. Refer to Coil Cassette Replacement - Bank 1 or Coil Cassette Replacement - Bank 2 . Is the action complete? | -- | System OK | -- | ||||||||||||||
21 | Inspect for poor connections at the ignition control module. Refer to Connector Repairs in Wiring Systems. If the condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | System OK | |||||||||||||||
22 | Replace the IC Module. Refer to Ignition Control Module Replacement - Bank 1 or Ignition Control Module Replacement - Bank 2 . Is the action complete? | -- | System OK | -- | ||||||||||||||
23 | Inspect for poor connections at the PCM. Refer to Connector Repairs in Wiring Systems. If the condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | System OK | |||||||||||||||
24 | Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | System OK | -- |
