Component Tests and General Diagnostics
CIRCUIT DESCRIPTIONThere 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.
DIAGNOSTIC AIDS
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.
^ 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, just-start the boots onto the spark plugs and then install the coil assembly as straight down onto the plugs as possible.
^ Ensure that 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(s) Replacement
TEST DESCRIPTION
Steps 1-7:
Steps 8-14:
Steps 15-24:
Steps 25-34:
The numbers below refer to the step numbers on the diagnostic table.
4. If any IC circuit diagnostic trouble codes (DTCs) are set, perform the DTC table first. If no IC circuit DTCs are set, inspect 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.
5. 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, inspect 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.
6. 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.
9. 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. Cuts Out, Misses
If the misfire disappears when running the engine using the J 26792-A Spark Plug Jumper Wires, and misfire is present when the boots are installed, replace the affected boot.
12. 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 and/or ignition coil cavity of the cam cover, inspect 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.
15. Ensure good DMM contact when measuring the spark plug resistance. When manufactured, the normal resistance for the spark plug is 3,000-8,000 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. Cuts Out, Misses
24. If the spark plug exhibits unusual signs of damage or deposits, diagnose and correct the root cause of the problem, such as excessive detonation, the wrong spark plug or an incorrect heat range for the application, a base engine problem, etc.
25. 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 light emitting diode (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 Ignition Module Tester is receiving adequate power and ground to perform the test. The Test button is used as an LED verification 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.