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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 DeVille 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Secondary Ignition 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 Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) .
       -  Fuel Injector Solenoid Coil Test - Engine Coolant Temperature 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 Mechanical.

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

The numbers below refer to the step numbers on the diagnostic table.

  1. 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.

    2.

  2. 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.

    3.

  3. Ensure good DMM contact when measuring spark plug resistance. When manufactured the normal resistance for the spark plug is 3000-8000 ohms.

  4. 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.

    5.

  5. 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.

Secondary Ignition Diagnosis

Step

Action

Values

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Are any of the following DTCs set?

    • DTC P0351 thru P0358
    • DTC P1359 or P1360
    • DTC P1372

--

Go to the applicable DTCs first

Go to Step 3

3
  1. Start the engine.
  2. Select the Misfire Bar Graph on the scan tool (the Misfire Current counters can also be used).

Do any cylinders indicate an excessive amount of misfire?

--

Go to Step 4

Go to Step 5

4

Is an entire bank of cylinders inoperative?

--

Go to Step 13

Go to Step 6

5

Select the Misfire History counters using the scan tool.

Do any cylinders indicate a history of misfiring?

--

Go to Step 6

System OK

6

The remaining steps are to be performed on the cylinder indicating the highest level of misfire.

  1. Disconnect the coil assembly from the spark plugs.
  2. Inspect the coil assembly, boots and spark plug insulators for the following conditions:
    3. • Visible cracks, deterioration or other damage
    • Carbon tracking or other signs of arcing
    • Missing or damaged spark plug boot springs
  3. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 24

Go to Step 7

7

  1. Using spark plug jumper wires J 36012, connect the coils to the spark plugs.
  2. Disconnect the spark plug on the affected cylinder and installJ 26792 spark tester.
  3. Remove the fuel injector fuses.
  4. Crank the engine and note the spark tester.

Does a spark jump the spark tester gap?

--

Go to Step 8

Go to Step 12

8

Remove the spark plug on the affected cylinder.

Does the spark plug show signs of oil or coolant entering the combustion chamber?

--

Go to step 17

Go to Step 9

9
  1. Check the spark plug for the following conditions:
    2. • Cracks
    • Excessive wear
    • Improper gap
    • Improper heat range and/or reach
    • Burned or damaged electrodes
    • Heavy deposits
    • Fouling
  2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 17

Go to Step 10

10

Measure the resistance of the affected spark plug.

Is the resistance less than the specified value?

15,000 ohms

Go to Step 11

Go to Step 17

11
  1. Install this spark plug in a different cylinder (swap the two spark plugs).
  2. Reconnect the coils to the plugs using the spark plug jumper wires.
  3. Reinstall the fuel injector fuses.
  4. Select the Misfire Bar Graph on the scan tool (the Misfire Current counters can also be used).
  5. Start the engine.

Did the misfire follow the spark plug?

--

Go to Step 17

Go to Diagnostic Aids

12

Important: Remove the fuel pump fuses 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.

  1. Turn OFF the ignition.
  2. Remove the fuel pump fuses.
  3. Disconnect the ignition control module harness connector.
  4. Connect the DMM between the ignition control circuit for the affected cylinder and ground.
  5. Set the DMM to AC Hertz.
  6. Measure the frequency on the ignition control circuit for the affected cylinder while cranking the engine.

Is the frequency within the specified range?

1-2 Hz

Go to Step 18

Go to Step 23

13

Check the affected bank for a loss of ignition module assembly power and/or ground.

If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 24

Go to Step 14

14

Using the DMM measure the resistance between the ground circuit and the reference low circuit in the ignition control module harness connector.

Does the DMM display the value shown (or lower)?

5 Ohms

Go to Step 15

Go to Step 16

15

Important: Remove the fuel pump fuses 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.

  1. Turn OFF the ignition.
  2. Disconnect the ignition control module harness connector.
  3. Connect the DMM between the ignition control circuit for the affected cylinder and ground.
  4. Set the DMM to AC Hertz.
  5. Measure the frequency on the ignition control circuit for the affected cylinder while cranking the engine.

Is the frequency within the specified range?

1-2 Hz

Go to Step 18

Go to Step 23

16

Repair the open/high resistance reference low circuit.

Is the action complete?

--

Go to Step 24

--

17

Important: If the spark plug is being replaced because of gas or oil fouling, the cause of the fouling must be determined before replacing the spark plug.

Replace the spark plug. Refer to Spark Plug Replacement in Engine Electrical.

Is the action complete?

--

Go to Step 24

--

18

Important: Remove the fuel injector fuses before proceeding.

  1. Turn OFF the ignition.
  2. Remove the ignition control module from the ignition coil assembly. If the mating connector (between the module and the coils) came off with the module, remove the mating connector and install it into the coil assembly.
  3. Reconnect the ignition control module to the engine harness.
  4. Connect the J 43298 ignition module tester to the ignition control module.
  5. Crank the engine while observing the tester.

Do four LEDs flash ON and OFF as the engine is cranked?

--

Go to Step 19

Go to Step 21

19

Check for poor terminal connections between the IC module and the coil assembly.

If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 24

Go to Step 20

20

Replace the affected coil assembly.

Is the action complete?

--

Go to Step 24

--

21

Check for poor terminal connection connections at the IC module.

If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 24

Go to Step 22

22

Replace the IC module. Refer to Ignition Control Module Replacement - Bank 1 or Ignition Control Module Replacement - Bank 2 .

Is the action complete?

--

Go to Step 24

--

23

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming

Is the action complete?

--

Go to Step 24

--

24
  1. Start the engine.
  2. Select the Misfire Bar Graph on the scan tool (the Misfire Current counters can also be used).

Do any cylinders indicate an excessive amount of misfire?

--

Go to Step 25

System OK

25

Is the misfire indicated on the same cylinders that were just diagnosed?

--

Go to Diagnostic Aids

Go to Step 3