GM Service Manual Online
For 1990-2009 cars only

Refer to Engine Controls Schematics

Front and Rear Ignition Control Modules


Object Number: 590096  Size: FS
Fuel Injector Fuses
Fuel Injector Fuses
Fuel Injector Fuses
Fuel Injector Fuses
Handling ESD Sensitive Parts Notice
Engine Controls Component Views
Powertrain Control Module Description
Crankshaft and Camshaft Position Sensor
PCM Power and Grounds
OBD II Symbol Description Notice
.

Circuit Description

The ignition system on this engine uses an individual ignition coil for each cylinder. An ignition coil assembly consisting of three coils and an ignition control module (ICM), is located in the center of each cam cover. This arrangement allows the ignition coil to connect directly to the spark plug using only a boot. This eliminates the need for secondary ignition wires. There are separate ignition modules for bank 1 and for bank 2. Each module controls the three ignition coils for that bank of cylinders. The powertrain control module (PCM) controls ignition module operation. There are six ignition control (IC) circuits, one per cylinder, that connect the PCM and the ignition modules. The ignition modules also have a power feed, a chassis ground circuit, and a reference low circuit each. The PCM causes spark to occur by pulsing the IC circuit, which signals the ignition module to trigger the ignition coil and fire the spark plug. Sequencing and timing are PCM controlled.

Conditions for Running the DTC

    • The ignition voltage is between 9.0-17.0 volts.
    • The conditions are met for less than 1.0 second.

Conditions for Setting the DTC

The PCM detects an incorrect voltage potential on the ignition control circuit.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The PCM turns the MIL OFF after 3 consecutive drive trips during which the diagnostic runs and passes.
    • A last test failed, or the current DTC, clears when the diagnostic runs and passes.
    • A History DTC clears after 40 consecutive warm-up cycles, if no other emission related diagnostic failures are reported.
    • Use a scan tool in order to clear the MIL diagnostic trouble code.
    • Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module Description , Clearing Diagnostic Trouble Codes.

Diagnostic Aids

Notice: Use the connector test adapter kit J 35616-A for any test that requires probing the following items:

   • The PCM harness connectors
   • The electrical center fuse/relay cavities
   • The component terminals
   • The component harness connector
Using this kit will prevent damage caused by the improper probing of connector terminals.

If the problem is intermittent, refer to Intermittent Conditions .

Test Description

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

  1. With no fault detected, the scan tool will display OK continuously. If a fault is detected, the display may fluctuate between OK and Fault, or display Fault continuously. If Fault is displayed, even momentarily, this should be considered fault present.

  2. Refer to the system mechanization for the fuses which supply these circuits.

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Start and idle the engine. If the engine will not start, refer to Engine Cranks but Does Not Run .
  2. Using the scan tool, monitor the ignition control status for this cylinder.

Does the scan tool continuously indicate OK?

--

Go to Diagnostic Aids

Go to Step 3

3

Is an entire bank of cylinders inoperative?

--

Go to Step 4

Go to Step 8

4

Are the ignition system fuses OK?

--

Go to Step 5

Go to Step 12

5

  1. Turn the key to OFF.
  2. Disconnect the harness connector from the ignition control module for the affected cylinders.
  3. Turn the key to ON.
  4. Using a test lamp connected to ground, probe the ignition feed circuit in the ignition control module harness.

Does the test lamp illuminate?

--

Go to Step 6

Go to Step 13

6

Connect a test lamp between the ignition feed circuit and the ground circuit in the ignition control module harness.

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 14

7

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

Is the resistance less than or equal to the specified value?

5 ohms

Go to Step 8

Go to Step 15

8

Important: Remove the fuel pump fuse 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 the key to OFF.
  2. Remove the fuel pump fuse.
  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?

2-20 Hz

Go to Step 19

Go to Step 9

9

  1. Turn the key to ON, with the engine OFF.
  2. Using the DMM, measure the voltage on the affected ignition control circuit.

Is the voltage more than the specified value?

1.0 V

Go to Step 18

Go to Step 10

10

  1. Turn the key to OFF.
  2. Disconnect the PCM.
  3. Using the DMM, check continuity of the ignition control circuit from the PCM harness connector to the ignition control module harness connector.

Is the resistance less than or equal to the specified value?

5 ohms

Go to Step 11

Go to Step 16

11

Using the DMM, check for continuity between the ignition control circuit and ground.

Is continuity indicated?

--

Go to Step 17

Go to Step 24

12

Check for a short to ground in the ignition control module ignition feed circuit.

Was a problem found and corrected?

--

Go to Step 26

Go to Step 21

13

Repair the open ignition control module ignition feed circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

14

Repair open ignition control module ground circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

15

Repair the open or high resistance ignition control module reference low circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

16

Repair the open or high resistance in the ignition control circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

17

Repair the ignition control circuit shorted to ground. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

18

Repair the ignition control circuit shorted to voltage. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

19

  1. Turn the key to OFF.
  2. Using the DMM, check for continuity between the affected ignition control circuit and all other IC circuits.

Is continuity indicated?

--

Go to Step 20

Go to Step 21

20

Repair the ignition control circuits that are shorted together. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 26

--

21

Check for poor connections and terminal tension at the ignition control module harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Was a problem found and corrected?

--

Go to Step 26

Go to Step 22

22

  1. Remove the ignition control module from the coil assembly. If the mating connector and seal came off with the module, remove these from the module and install them onto the coil assembly. With the mating connector removed, the module will have a female connector cavity with male pins.
  2. Reconnect the harness to the ignition control module.
  3. Connect the J 43298 ignition noid lamp to the module.
  4. Crank the engine and observe the light emitting diodes (LEDs) on the tester.

Do the LEDs flash for all three cylinders?

--

Go to Diagnostic Aids

Go to Step 23

23

Replace the ignition control module. Refer to Ignition Control Module Replacement .

Is the action complete?

--

Go to Step 26

--

24

Check for poor connections and terminal tension at the PCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Was a problem found and corrected.

--

Go to Step 26

Go to Step 25

25

Important: The replacement PCM must be programmed.

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

Is the action complete?

--

Go to Step 26

--

26

  1. Clear the DTCs with the scan tool.
  2. Turn the key to OFF and wait 15 seconds.
  3. Operate the vehicle within the conditions that are required for this diagnostic to run. Refer to the Conditions for Running the DTC.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 27

Go to Step 2

27

Review Captured Info using the scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to the applicable DTC table

System OK