There are two separate ignition module assemblies, one for each bank of cylinders. Each assembly contains an ignition control (IC) module and three ignition coils. Each IC module consists of the following circuits:
• | Ignition 1 voltage |
• | Ground |
• | IC timing low reference |
• | IC control circuits for cylinders 1-6 |
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.
When servicing the ignition system components, use the following recommended procedures:
• | If a boot remains attached to a coil or a spark plug, twist the boot prior to removal. Use the J 43094 Spark Plug Boot Removal Tool. |
• | Check 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, just-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 the cover. |
• | Repair a torn perimeter seal with an RTV sealant. |
• | Adhere to the torque specifications when installing the cassette to the cam cover and the module to the cassette. Refer to Fastener Tightening Specifications and Ignition Coil Replacement . |
The numbers below refer to the step numbers on the diagnostic table.
If any IC circuit DTCs are set, perform the DTC table first. If no IC circuit DTCs are set, check the IC Circuit Status for all cylinders. If an IC Circuit Status indicates anything other than OK, even momentarily, perform the corresponding IC circuit DTC table as if the DTC were set.
A misfiring or dead cylinder can sometimes affect the misfire counters for other cylinders. When performing this table, concentrating on the cylinder with the highest level of misfire and correcting the problem may also correct the other cylinders that indicate misfire. If multiple cylinders are suspected, perform each test on all affected cylinders. An ignition coil, the boots, or the spark plugs may fail only when moisture is present. Although difficult to test on this engine, selectively wetting down parts of the system and rechecking for a misfire or any arcing may uncover a problem with one or more components. If moisture is present in the spark plug and ignition coil cavity of the cam cover, check the perimeter seal for damage. Repair tears in the perimeter seal with an RTV sealant. Ensure that the 7 cassette mounting bolts are tightened to the specified torque. Refer to Ignition Coils Replacement .
The J 26792 spark tester (ST 125) presents a more difficult load on the secondary ignition than a normal spark plug. If a miss, a stumble, or a hesitation is being caused by a spark plug not firing, the spark tester should also not fire.
A suspected ignition system miss may actually be a fuel system problem. Perform the Cuts Out, Misses , if the diagnosis has not yet been performed. An internal engine problem can also cause a driveability concern. Refer to Base Engine Misfire Diagnosis .
If the misfire disappears when running the engine using the J 36012 Spark Plug Jumper wires, and misfire is present when the boots are installed, replace the affected boot.
An ignition coil, the boots, or the spark plugs may fail only when moisture is present. Although difficult to test on this engine, selectively wetting down parts of the system and rechecking for a misfire or any arcing may uncover an intermittent problem. If moisture is present in the spark plug/ignition coil cavity of the cam cover, check the perimeter seal for damage. Repair tears in the perimeter seal with an RTV sealant. Ensure that the 7 cassette mounting bolts are tightened to the specified torque. Refer to Ignition Coil(s) Replacement .
Ensure good DMM contact when measuring the spark plug resistance. When manufactured, the normal resistance for the spark plug is 3000-8000 ohms. A suspected ignition system miss may actually be a fuel system problem. Perform the Cuts Out, Misses. An internal engine problem can also cause a driveability concern. Refer to Base Engine Misfire Diagnosis .
If the spark plug exhibits unusual signs of damage or deposits, diagnose and correct the root cause of the problem (e.g. excessive detonation, the wrong spark plug or an incorrect heat range for the application, a base engine problem, etc.).
Be sure to use the correct adaptor harness when connecting the ignition module tester to the LX5 engine. 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 simply 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 4 red LEDs. To use this function, connect the tool, turn the ignition switch to run, then momentarily press the Test button. All 4 red LEDs should come on brightly. The crank the vehicle. If the 3 red LEDs flash, this confirms correct operation of the primary ignition system. The ignition module tester may get hot during actual testing as the tester is attempting to simulate the load of the ignition coils' primary windings.
Only 3 of the red LEDs are used when testing the LX5 engine. Four LEDs are provided on the tester for 8-cylinder applications.
If 3 LEDs flash, the module output drivers are operating. If one or more LEDs are inoperative, excluding the one unused LED, and no IC circuit DTCs are set, replace the module.
Step | Action | Value(s) | Yes | No | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference:
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1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||||
2 |
Do any cylinders indicate an excessive amount of misfire? | -- | Go to Step 3 | Go to Step 11 | ||||||||||||
3 | Is an entire bank of cylinders inoperative? | -- | Go to Step 16 | Go to Step 4 | ||||||||||||
Are any IC circuit DTCs set, or does the IC Circuit Status for any cylinder indicate anything other than OK? | -- | Go to Step 5 | ||||||||||||||
The remaining steps are to be performed on the cylinder indicating the highest level of misfire.
Did you find a problem? | -- | Go to Step 20 | Go to Step 6 | |||||||||||||
Does a spark jump the tester gap? | -- | Go to Step 7 | Go to Step 10 | |||||||||||||
7 | Remove the spark plug on the affected cylinder. Does the spark plug show signs of oil or coolant entering the combustion chamber? | -- | Go to Symptoms - Engine Mechanical in Engine Mechanical | Go to Step 8 | ||||||||||||
8 | Inspect the spark plug for the following conditions:
Refer to Spark Plug Inspection . Did you find a problem? | -- | Go to Step 24 | Go to Step 9 | ||||||||||||
Did the misfire follow the spark plug? | -- | Go to Step 24 | Go to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical | |||||||||||||
10 |
Important: Remove the fuel pump fuse before proceeding. Running or cranking the engine with an ignition control module disconnected will cause excessive engine fueling if the fuel pump is not disabled. Does the frequency measure within the specified range? | 2-20 Hz | Go to Step 25 | Go to Step 30 | ||||||||||||
11 | Select the Misfire History counters using the scan tool. Do any cylinders indicate a history of misfiring? | -- | Go to Step 12 | Go to Step 33 | ||||||||||||
The remaining steps are to be performed on the cylinder indicating the highest level of misfire.
Did you find a problem? | -- | Go to Step 20 | Go to Step 13 | |||||||||||||
13 | Does the spark plug show signs of oil or coolant entering the combustion chamber? | -- | Go to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical | Go to Step 14 | ||||||||||||
14 |
Did you find a problem? | -- | Go to Step 24 | Go to Step 15 | ||||||||||||
Measure the resistance of the affected spark plugs. Does the resistance measure less than the specified value? | 15K ohms | Go to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical | Go to Step 24 | |||||||||||||
16 |
Does the test lamp illuminate? | -- | Go to Step 17 | Go to Step 21 | ||||||||||||
17 | Connect a test lamp between the Ignition feed circuit and the ground circuit in the ignition control module harness. Does the test lamp illuminate? | -- | Go to Step 18 | Go to Step 22 | ||||||||||||
18 | Using the DMM, measure the resistance between the ground circuit and the Reference Low circuit in the harness connector of the ignition control module . Does the resistance measure less than or equal to the specified value? | 5 ohms | Go to Step 19 | Go to Step 23 | ||||||||||||
19 |
Important: Remove the fuel pump fuse before proceeding. Running or cranking the engine with an ignition control module disconnected will cause excessive engine fueling if the fuel pump is not disabled. Does the frequency measure within the specified range for all circuits tested? | 2-20 Hz | Go to Step 25 | Go to Step 30 | ||||||||||||
20 | Perform any repairs as necessary. Did you complete the repairs? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
21 | Repair the open or high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
22 | Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
23 | Repair the open or high resistance in the low reference circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
Replace the spark plugs as necessary. Refer to Spark Plug Replacement in Engine Electrical. Did you complete the replacement? | -- | Go to Step 31 | Go to Step 33 | |||||||||||||
Important: Remove the fuel pump fuse before proceeding. Running or cranking the engine with an ignition control module disconnected will cause excessive engine fueling if the fuel pump is not disabled. Do 3 LEDs flash on and off as the engine is cranked? | -- | Go to Step 26 | Go to Step 28 | |||||||||||||
26 | Check for poor connections or terminal tension between the IC module and the coil assembly. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems . Did you find and correct the condition? | -- | Go to Step 31 | Go to Step 27 | ||||||||||||
27 | Replace the affected coil assembly. Refer to Ignition Coil Replacement . Did you complete the replacement? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
28 | Check for poor connections or terminal tension at the IC module. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems . Was a problem found and corrected? | -- | Go to Step 31 | Go to Step 29 | ||||||||||||
29 | Replace the ignition control module. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
30 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement Did you complete the replacement? | -- | Go to Step 31 | Go to Step 33 | ||||||||||||
31 |
Do any cylinders indicate an excessive amount of misfire? | -- | Go to Step 32 | Go to Step 33 | ||||||||||||
32 | Is the misfire indicated on the same cylinders that were just diagnosed? | -- | Go to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical | Go to Step 3 | ||||||||||||
33 |
Does the scan tool indicate that this test passed? | -- | Go to Step 34 | Go to Step 2 | ||||||||||||
34 | Select the Capture Info option and the Review Info option with the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |