Circuit Description
There are two separate ignition module assemblies, one for each bank of cylinders. Each assembly contains an ignition control (IC) module and four ignition coils. Each IC module consists of the following circuits:
| • | Ignition 1 voltage |
| • | Ground |
| • | IC timing low reference |
| • | IC circuits for cylinders 1-8 |
Each ignition coil connects directly to its spark plug via a short boot. The IC circuits transmit timing pulses from the powertrain control module (PCM) to the IC modules, which triggers the coils to fire the plugs in the correct sequence. The PCM monitors each IC circuit for improper voltage levels.
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 Symptoms - Engine Mechanical in Engine Mechanical 4.6L. |
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 J 43298 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 J 43298 Ignition Module Tester 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 ignition control (IC) Circuit (DTC P0351-P0358), or IC Circuit Group (DTC P1359 and/or DTC P1360) are set, replace the module.
Step | Action | Value(s) | Yes | No | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||||
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 before proceeding with this table. Do any of the following DTCs set?
| -- | Go to DTC P0300 | Go to Step 3 | ||||||||||||||
3 |
Do any of the cylinders indicate an excessive amount of misfire? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||||||||||
4 |
Does the test lamp illuminate? | -- | Go to Step 5 | Go to Step 14 | ||||||||||||||
5 | Probe the ignition control module ground circuit with a test lamp connected to battery voltage. Does the test lamp illuminate? | -- | Go to Step 6 | Go to Step 15 | ||||||||||||||
6 |
Does the frequency measure within the specified range? | 1-2 Hz | Go to Step 7 | Go to Step 12 | ||||||||||||||
Did you find and correct the condition? | -- | Go to Step 24 | Go to Step 8 | |||||||||||||||
Does a spark jump the tester gap and is the spark consistent? | -- | Go to Step 9 | Go to Step 13 | |||||||||||||||
9 |
Important: If the spark plug shows signs of oil or coolant fouling, refer to Base Engine Misfire with Coolant Consumption or Base Engine Misfire with Excessive Oil Consumption 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 contamination? | -- | Go to Step 17 | Go to Step 10 | ||||||||||||||
10 | Inspect the spark plug for the following conditions: Refer to Spark Plug Inspection .
Did you find a condition with the spark plug? | -- | Go to Step 17 | Go to Step 11 | ||||||||||||||
11 |
Did the misfire move with the spark plug? | -- | Go to Step 17 | Go to Base Engine Misfire without Internal Engine Noises in Engine Mechanical | ||||||||||||||
12 |
Does the DMM display continuity? | -- | Go to Step 22 | Go to Step 16 | ||||||||||||||
Important: Ensure that the green power LED is illuminated before proceeding. Do four LEDs flash ON and OFF as the engine is cranked? | -- | Go to Step 18 | Go to Step 20 | |||||||||||||||
14 | Repair the ignition control module ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||||||||||
15 | Repair the ignition control module ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||||||||||
16 | Repair the ignition control circuit for an open. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 24 | -- | ||||||||||||||
17 | Replace the spark plug. Refer to Spark Plug Replacement in Engine Electrical. Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||||
18 | 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? | -- | Go to Step 24 | Go to Step 19 | ||||||||||||||
19 | Replace the affected coil assembly. Refer to Ignition Coil Replacement - Bank 2 or Ignition Coil Replacement - Bank 1 . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||||
20 | 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? | -- | Go to Step 24 | Go to Step 21 | ||||||||||||||
21 | Replace the IC Module. Refer to Ignition Control Module Replacement - Bank 2 or Ignition Control Module Replacement - Bank 1 . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||||
22 | 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? | -- | Go to Step 24 | Go to Step 23 | ||||||||||||||
23 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 24 | -- | ||||||||||||||
24 |
Does vehicle operate normally, with no MIL illumination or stored DTCs? | -- | System OK | Go to DTC P0300 | ||||||||||||||
