Electronic Ignition (EI) System Diagnosis

CIRCUIT DESCRIPTION
The Secondary Ignition Diagnosis tests the spark plugs, coils and IC modules. Diagnosis of the Ignition Control (IC) circuits is covered in DTCs P0351 through P0358, and DTC P1359 and P1360. This table requires the following special tools:
^ J 26792 spark tester (ST-125)
^ J 43883 spark plug jumper wires
^ J 43298 ignition module tester

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.
^ 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.
^ Repair a torn perimeter seal with RTV sealant.
^ Adhere to the torque specifications when installing the cassette to the cam cover and the module to the cassette.

A suspected ignition system miss may actually be a problem other than the secondary ignition system. Check the following items:
^ Fuel System
- Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2.
- Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F).
- Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Outside 10-35 Degrees C (50-95 Degrees F).
^ Engine Mechanical
Check for base engine conditions that could produce an engine misfire. Refer to Base Engine Misfire Diagnosis in Engine. Engine

A spark plugs resistance, as measured outside the cylinder, may indicate a resistance within specified values. However, the spark plug is not being placed under the same operating conditions as it is in the cylinder. If the spark plug resistance is OK, but the miss follows a spark plug when swapped with a known good cylinder, the spark plug is suspect and should be replaced.

If the misfire is gone when running the engine using the J 43883 Spark Plug Jumper wires, and misfire is present when the boots are installed, replace the affected boot.

TEST DESCRIPTION

Steps 1 - 10:

Steps 11 - 17:

Steps 18 - 25:

The numbers below refer to the step numbers on the diagnostic table.
6. An Ignition coil, the boots or 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 misfire or 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 RTV sealant. Ensure that the cassette mounting bolts are tightened to the specified torque. Refer to Coil Cassette Replacement - Bank 1 or Coil Cassette Replacement - Bank 2.
7. The J 26792 spark tester (ST 125) presents a more difficult load on the secondary ignition than a normal spark plug. If a miss, stumble, or hesitation is being caused by a spark plug not firing, the spark tester should also not fire.
10. Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 3000-8000 ohms.
17. If the spark plug exhibits unusual signs of damage or deposits, the root cause of the problem such as excessive detonation, wrong spark plug/incorrect heat range for application, a base engine problem, etc., should be corrected before replacing the spark plugs.
18. Be sure to 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 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 four red LEDs. To use this function, connect the tool, turn the ignition to run, then momentarily press the Test button. All four red LEDs should come on brightly. The crank the vehicle. If the four red LEDs flash, this confirms proper operation of the primary ignition system (e.g. 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.