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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2003 🢒 Aurora 🢒 Engine 🢒 Engine Electrical 🢒 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. Both IC modules consist of the following circuits:

    • The ignition 1 voltage circuit
    • The ground circuit
    • The IC circuits for cylinders 1, 3, 5, 7 on bank 1 ignition module
    • The IC circuits for cylinders 2, 4, 6, 8 on bank 2 ignition module
    • The IC module low reference circuit

Each ignition coil connects directly to its spark plug through a wire spring conductor housed in a short spark plug boot. The IC circuits transmit timing pulses from the powertrain control module (PCM) to the IC modules which triggers the ignition coils in the proper sequence for spark plug firing. The PCM monitors each IC circuit for improper voltage levels. If an improper voltage level is detected on an IC circuit a DTC will set.

Diagnostic Aids
    • Other electrical, fuel, or mechanical conditions can cause an engine to crank but does not run, or set a DTC P0300 misfire code.
    • This Electronic Ignition (EI) System diagnostic table assumes that the vehicle battery is fully charged. Refer to Battery Inspection/Test in Engine Electrical.
    • 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 ignition system and monitoring for a misfire may help in isolation an intermittent condition. Replace any worn or torn spark plug boots or seals.
    • Intermittent conditions--Refer to Intermittent Conditions .

Test Description

The numbers below refer to the numbers in the diagnostic table.

  1. This step tests for a short to battery positive voltage on the ignition 1 voltage circuit. When the ignition is turned OFF, the test lamp should not illuminate at the DIS fuse.

    2.

  2. The Spark Tester places a higher load, up to 25,000 volts, on the secondary ignition than a normal spark plug.

Step

Action

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

Attempt to start the engine.

Does the engine start and run?

Go to Step 14

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Remove the underhood fuse block cover.
  3. Probe the DIS fuse in the underhood fuse block with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate on any test points of the fuse?

Go to Step 35

Go to Step 4

4
  1. Turn ON the ignition with the engine OFF.
  2. Probe the DIS fuse in the underhood fuse block with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate on both test points of the fuse?

Go to Step 11

Go to Step 5

5

Does the test lamp illuminate on one test point of the DIS fuse?

Go to Step 6

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

6
  1. Turn OFF the ignition.
  2. Disconnect the ignition control (IC) module bank 1 electrical connector.
  3. Test the ignition 1 voltage circuit between the DIS fuse and the IC module bank 1 for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 43

Go to Step 7

7
  1. Turn OFF the ignition.
  2. Disconnect the ignition control (IC) module bank 2 electrical connector.
  3. Test the ignition 1 voltage circuit between the DIS fuse and the IC module bank 2 for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 43

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Replace the open DIS fuse.
  3. Connect the IC module bank 1 electrical connector.
  4. Turn ON the ignition, with the engine OFF.

Does the DIS fuse open?

Go to Step 9

Go to Step 10

9
  1. Turn OFF the ignition.
  2. Replace the open DIS fuse.
  3. Disconnect the IC module bank 1 electrical connector.
  4. Remove the IC module from the ignition coil assembly bank 1. Refer to Ignition Control Module Replacement - Bank 1 .
  5. Connect a 10-amp fused jumper wire between the ignition 1 voltage circuit of the IC module electrical connector and the ignition 1 voltage terminal of the IC module bank 1. Refer to Using Fused Jumper Wires in Wiring Systems.
  6. Connect a jumper wire between the ground circuit of the IC module electrical connector and the ground terminal of the IC module bank 1.
  7. Turn ON the ignition, with the engine OFF.

Does the fuse in the jumper wire open?

Go to Step 23

Go to Step 25

10
  1. Turn OFF the ignition.
  2. Disconnect the IC module bank 2 electrical connector.
  3. Remove the IC module from the ignition coil assembly bank 2. Refer to Ignition Control Module Replacement - Bank 2 .
  4. Connect a 10-amp fused jumper wire between the ignition 1 voltage circuit of the IC module electrical connector and the ignition 1 voltage terminal of the IC module bank 2. Refer to Using Fused Jumper Wires in Wiring Systems.
  5. Connect a jumper wire between the ground circuit of the IC module electrical connector and the ground terminal of the IC module bank 2.
  6. Turn ON the ignition, with the engine OFF.

Does the fuse in the jumper wire open?

Go to Step 24

Go to Step 26

11
  1. Turn OFF the ignition.
  2. Disconnect the IC module electrical connector bank 1.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the IC module electrical connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 12

Go to Step 29

12
  1. Turn OFF the ignition.
  2. Disconnect the IC module electrical connector bank 2.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the IC module electrical connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 13

Go to Step 30

13
  1. Turn OFF the ignition.
  2. Probe the ground circuit of the IC module bank 1 electrical connector with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 32

Go to Step 31

14

Observe the Misfire Current Counters with a scan tool.

Do any of the cylinders indicate an increasing misfire count?

Go to Step 15

Go to Intermittent Conditions

15
  1. Turn OFF the ignition.
  2. Disconnect the IC module for the cylinders which indicated a misfire.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the IC module with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 16

Go to Step 33

16
  1. Turn OFF the ignition.
  2. Probe the ground circuit of the IC module electrical connector for the bank of cylinders identified as misfiring with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors and Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

Go to Step 17

Go to Step 34

17
  1. Turn OFF the ignition.
  2. Disconnect the ignition coil assembly from the spark plugs on the bank of cylinders which indicated a misfire condition. Refer to Ignition Coil Replacement - Bank 1 or Ignition Coil Replacement - Bank 2 .
  3. Inspect the ignition coil housing assembly and the spark plug boots for the following:
    4. • Any visible cracks, deterioration, or other damage
    • Any carbon tracking or other signs of arcing
    • Any missing or damaged spark plug boot springs
    • A missing, loose, or corroded grounding spring from coil housing to cam cover
  4. Replace the component if the inspection reveals a concern.

Did you find and correct the condition?

Go to Step 44

Go to Step 18

18

  1. Connect the electrical connector to the IC module.
  2. Install the J 36012-A Ignition System Diagnosis Harness spark plug jumper wires between the ignition coils and the spark plugs.
  3. Connect the J 26792 HEI Spark Tester to the spark plug jumper wire for the cylinder identified as misfiring.
  4. Attach the clamp end of the J 26792 to a good engine ground.
  5. Attach a jumper wire from the grounding spring on the ignition coil housing to a good engine ground.
  6. Remove both fuel injector fuses.
  7. Observe the J 26792 .

    8. Caution: The ignition coils secondary voltage output capabilities are very high-more than 40,000 volts. Avoid body contact with high ignition voltage secondary components when the engine is running, to prevent personal injury.

  8. Crank the engine.

Does the spark jump the tester gap?

Go to Step 19

Go to Step 22

19

Remove the spark plug for the cylinder that was identified as misfiring. Refer to Spark Plug Replacement .

Does the spark plug indicate oil contamination?

Go to Base Engine Misfire with Excessive Oil Consumption in Engine Mechanical

Go to Step 20

20

Does the spark plug indicate coolant contamination?

Go to Base Engine Misfire with Coolant Consumption in Engine Mechanical

Go to Step 21

21
  1. Exchange the suspected spark plug with a spark plug from a different cylinder. Refer to Spark Plug Replacement .
  2. Install the J 36012-A spark plug jumper wires between the ignition coils and the spark plugs for the affected cylinder bank.
  3. Install a jumper wire between the coil housing ground spring and a good engine block ground.
  4. Install both fuel injector fuses.
  5. Monitor the misfire current counters with a scan tool.
  6. Start the engine.

Does the misfire move with the spark plug?

Go to Step 38

Go to Base Engine Misfire without Internal Engine Noises in Engine Mechanical

22
  1. Turn OFF the ignition.
  2. Remove the IC module from the ignition housing assembly. Refer to Ignition Control Module Replacement - Bank 1 or Ignition Control Module Replacement - Bank 2 . If the intermediate mating connector came off with the IC module, remove the mating connector.
  3. Connect the engine harness electrical connector to the IC module.

    4. Important: Use the correct test harness when connecting the J 43298 Ignition Module Tester to the IC module.

  4. Connect the J 43298 to the IC module.

    5. Important: The green power LED on the J 43298 must be illuminated when the ignition is ON.

  5. Turn ON the ignition, with the engine OFF.
  6. Observe the J 43298 .

    7. Important: Momentarily press the test button on the J 43298 . All four red LEDs should turn ON brightly.

  7. Crank the engine.

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

Go to Step 27

Go to Step 28

23

Test for an intermittent and for a poor connection at the IC module bank 1 electrical connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 44

Go to Step 39

24

Test for an intermittent and for a poor connection at the IC module bank 2 electrical connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 44

Go to Step 40

25

Test for an intermittent and for a poor connection at the intermediate mating connector between the IC module and the ignition coil assembly bank 1. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 44

Go to Step 41

26

Test for an intermittent and for a poor connection at the intermediate mating connector between the IC module and the ignition coil assembly bank 2. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 44

Go to Step 42

27

Test for an intermittent and for a poor connection at the intermediate mating connector between the affected IC module and the ignition coil assembly. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 44

Go to Step 36

28

Test for an intermittent and for a poor connection at the electrical connector of the IC module for the cylinders which indicated a misfire. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 44

Go to Step 37

29

Repair the high resistance or the open in the ignition 1 voltage circuit of the IC module bank 1. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

30

Repair the high resistance or the open in the ignition 1 voltage circuit of the IC module bank 2. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

31

Repair the high resistance or the open in the ground circuit of the IC module bank 1. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

32

Repair the high resistance or the open in the ground circuit of the IC module bank 2. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

33

Repair the high resistance or the open in the ignition 1 voltage circuit of the affected IC module. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

34

Repair the high resistance or the open in the ground circuit of the affected IC module. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

35

Repair the short to battery voltage in the ignition 1 voltage circuit to the IC modules. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 44

--

36

Replace the affected ignition coil assembly. Refer to Ignition Coil Replacement - Bank 1 or Ignition Coil Replacement - Bank 2 .

Did you complete the replacement?

Go to Step 44

--

37

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

Did you complete the replacement?

Go to Step 44

--

38

Replace the spark plug. Refer to Spark Plug Replacement .

Did you complete the replacement?

Go to Step 44

--

39

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

Did you complete the replacement?

Go to Step 44

--

40

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

Did you complete the replacement?

Go to Step 44

--

41

Replace the ignition coil assembly bank 1. Refer to Ignition Coil Replacement - Bank 1 .

Did you complete the replacement?

Go to Step 44

--

42

Replace the ignition coil assembly bank 2. Refer to Ignition Coil Replacement - Bank 2 .

Did you complete the replacement?

Go to Step 44

--

43

Replace the DIS fuse.

Did you complete the replacement?

Go to Step 44

--

44

Were you sent to this diagnostic table from the Engine Cranks But Does Not Run diagnostic table?

Go to Step 46

Go to Step 45

45

Were you sent to this diagnostic table from the DTC P0300 diagnostic table?

Go to Step 47

Go to Step 48

46

Attempt to start the engine.

Does the engine start and run?

Go to Step 48

Go to Engine Cranks but Does Not Run

47
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the conditions for running the DTC P0300. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail during this ignition cycle?

Go to DTC P0300

Go to Step 48

48

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK