GM Service Manual Online
For 1990-2009 cars only

Circuit Description

There are three dual-tower ignition coils that are part of the ignition control module (ICM). The ICM contains coil driver circuits that command the coils to operate. The ICM has the following circuits:

    • An ignition voltage circuit
    • A ground
    • An IC 1 control circuit for the 1-4 ignition coil
    • An IC 2 control circuit for the 2-5 ignition coil
    • An IC 3 control circuit for the 3-6 ignition coil
    • A low reference circuit

The powertrain control module (PCM) controls each dual-tower ignition coil by transmitting timing pulses on the IC control circuit to the ICM for the proper coil to enable a spark event.

If the PCM detects a short to ground in one of the IC control circuits, it will set the following corresponding DTC:

    • DTC P1361 for IC 1 control circuit
    • DTC P1362 for IC 2 control circuit
    • DTC P1363 for IC 3 control circuit

If the PCM detects a short to voltage in one of the IC control circuits, it will set the following corresponding DTC:

    • DTC P1351 and DTC P1361 for IC 1 control circuit
    • DTC P1352 and DTC P1362 for IC 2 control circuit
    • DTC P1353 and DTC P1363 for IC 3 control circuit

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

The PCM detects a short to ground or voltage in the IC control circuit for 30 out of 100 engine cycles.

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.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check -- Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 3

Go to Intermittent Conditions

3

Is DTC P1351, P1352, or P1353 also set?

--

Go to DTC P1351, P1352, or P1353

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the ignition control module (ICM).
  3. Remove the fuel pump relay.
  4. Measure in DC Hertz between the affected IC control circuit of the ICM and a good ground with a DMM.
  5. Crank the engine.

Is the frequency within the specified range?

3-20 Hz

Go to Step 6

Go to Step 5

5

Test the IC control circuit of the ICM for an short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

6

Test for shorted terminals or a poor connection at the ICM. 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 10

Go to Step 8

7

Test for shorted terminals or for a poor connection at the powertrain control module (PCM). Refer Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

--

Go to Step 10

--

9

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10

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

Did the DTC fail this ignition?

--

Go to Step 3

Go to Step 11

11

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK