GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The ignition system on this engine uses an individual ignition coil for each cylinder. The powertrain control module (PCM) controls the ignition system operation. The PCM controls each coil using one of eight ignition control (IC) circuits. The PCM commands the IC circuit low when a spark event is requested. This causes the IC module to energize the ignition coil to create a spark at the spark plug. Each ignition coil has the following circuits:

    • An ignition positive voltage circuit
    • A ground circuit
    • An IC circuit
    • A reference low circuit

Sequencing and timing are PCM controlled. This DTC sets when the IC circuit is out of range.

Conditions for Running the DTC

The engine is operating.

Conditions for Setting the DTC

    • The PCM detects that the ignition control circuit is grounded, open, or shorted to voltage.
    • The above conditions are met for less than 1 second.

Action Taken When the DTC Sets

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

Conditions for Clearing the MIL/DTC

    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

Test Description

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

  1. This step verifies the integrity of the IC circuit and the PCM output.

  2. This step tests for a short to ground on the ignition control circuit.

Step

Action

Values

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: If all of the ignition control (IC) DTCs are set at the same time, inspect the IC ground circuits and the B+ circuits for an open.

  1. Connect a scan tool.
  2. Start the engine.
  3. Monitor the IC status for the cylinder with the ignition control DTC using the scan tool.

Does the scan tool indicate Fault?

--

Go to Step 4

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC, or within the parameters observed in the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn OFF the engine.
  2. Disconnect the respective ignition coil electrical connector.
  3. Start the engine.
  4. Measure the frequency at the ignition control signal circuit using the DMM set to DC Hertz. Refer to Measuring Frequency in Wiring Systems.

Is the frequency within the specified range?

3-20 Hz

Go to Step 8

Go to Step 5

5

Measure the voltage at the ignition control signal circuit using the DMM.

Is the voltage more than the specified value?

1 V

Go to Step 14

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector.
  3. Test the continuity from the ignition control circuit at the ignition coil electrical connector to the PCM connector using the DMM. Refer to Testing for Continuity in Wiring Systems.

Does the DMM indicate continuity?

--

Go to Step 7

Go to Step 15

7

Test the respective ignition control circuit for a short to ground. Refer to Testing for Short to Ground in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 16

8

  1. Turn ON the ignition, with the engine OFF.
  2. Probe the ignition 1 voltage circuit of the ignition coil with a test lamp connected to battery ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 10

9

Probe the ground circuit of the ignition coil with a test lamp connected to B+. Refer to Troubleshooting with a Test Lamp in Wiring Systems.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 11

10

Repair the open in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

11

Repair the open in the ground circuit for the ignition coil. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

12

Inspect for poor connections at the harness connector of the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 13

13

Replace the ignition coil. Refer to Ignition Coil Replacement .

Did you complete the replacement?

--

Go to Step 18

--

14

Repair the ignition control circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

15

Repair the ignition control circuit for an open circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

16

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

17

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 18

--

18

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 19

Go to Step 2

19

Use a scan tool in order to observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK