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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 DeVille 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 Electronic Ignition (EI) System Diagnosis

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 that 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 the proper operation of 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 Mechanical
        Test for base engine conditions that could produce an engine misfire. Refer to Symptoms - Engine Mechanical in Engine Mechanical.

Test Description

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

  1. 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.

    2.

  2. The J 26792 Spark Tester (ST 125) places a higher load on the secondary ignition than a normal spark plug.

    3.

  3. 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

Go to Diagnostic System Check - Engine Controls

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?

    • DTCs P0351-P0358
    • DTCs P1359 or P1360
    • DTC P1372

--

Go to DTC P0300

Go to Step 3

3
  1. Start the engine.
  2. Monitor the Misfire Current counters with the scan tool.

Do any of the cylinders indicate an excessive amount of misfire?

--

Go to Step 4

Go to Intermittent Conditions

4
  1. Disconnect the appropriate ignition control module harness connector.
  2. Probe the ignition control module ignition 1 voltage circuit with a test lamp connected to a good ground.

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
  1. Turn OFF the ignition.
  2. Remove the fuel pump fuse.
  3. Disconnect the appropriate ignition control module (ICM) harness connector.
  4. Connect a DMM between the Ignition Control circuit for the affected cylinder and ground.
  5. Set the DMM to AC Hertz.
  6. Measure the frequency from the ignition control circuit for the affected cylinder while cranking the engine.

Does the frequency measure within the specified range?

1-2  Hz

Go to Step 7

Go to Step 12

7

  1. Turn OFF the ignition.
  2. Disconnect the appropriate ignition control module/coil assembly from the spark plugs. Refer to Ignition Coil Replacement - Bank 1 or Ignition Control Module Replacement - Bank 2 .
  3. Inspect the ignition coil assembly, boots and spark plug insulators for the following conditions:
    4. • Visible cracks, deterioration or other damage
    • Carbon tracking or other signs of arcing
    • Missing or damaged spark plug boot springs
  4. If the condition is found, repair as necessary.

Did you find and correct the condition?

--

Go to Step 24

Go to Step 8

8

  1. Install the ignition control module harness connector.
  2. Remove the fuel pump fuse.
  3. Install J 36012-A Spark Plug Jumper Wires between the ignition coils and the spark plugs.
  4. Install the J 26792 Spark Tester to the spark plug wire for affected cylinder.
  5. Crank the engine and observe the spark tester.

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 .

    • Cracked insulator
    • Excessive wear
    • Improper gap
    • Improper heat range and/or reach
    • Burned or damaged electrode
    • Heavy deposits
    • Fouling

Did you find a condition with the spark plug?

--

Go to Step 17

Go to Step 11

11
  1. Install spark plug in a different cylinder (swap the two spark plugs).
  2. Install the spark plug jumper wire.
  3. Install the fuel pump fuse.
  4. Start the engine.
  5. Monitor the Misfire Current counters with a scan tool.

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
  1. Disconnect the PCM connectors. Refer to Powertrain Control Module Replacement .
  2. Test the continuity of the ignition control circuit with a DMM. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity?

--

Go to Step 22

Go to Step 16

13

  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. Install the ignition control module harness connector.
  4. Connect the J 43298 Ignition Module Tester (in place of the ignition coils) to the ignition control module.
  5. Turn ON the ignition with the engine OFF.

    6. Important: Ensure that the green power LED is illuminated before proceeding.

  6. Crank the engine while observing the tester.

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
  1. Reconnect all components.
  2. Operate vehicle.
  3. Observe MIL illumination, check for stored DTCs.

Does vehicle operate normally, with no MIL illumination or stored DTCs?

--

System OK

Go to DTC P0300