GM Service Manual Online
For 1990-2009 cars only

Circuit Description

There are 3 dual-tower ignition coils integrated with the ignition control module (ICM). The ICM contains coil driver circuits that operate the 3 coils. The ICM wiring includes the following circuits:

    • An ignition 1 voltage circuit
    • A ground circuit
    • An ignition coil 1 control circuit
    • An ignition coil 2 control circuit
    • An ignition coil 3 control circuit
    • A low reference circuit

The powertrain control module (PCM) controls each ignition coil by transmitting timing pulses to the ICM on each of the ignition coil control circuits to enable properly timed spark events. The ignition coil 1 controls spark for cylinders 1 and 4. The ignition coil 2 controls spark for cylinders 2 and 5. The ignition coil 3 controls spark for cylinders 3 and 6.

If the PCM detects an incorrect voltage on any of the ignition coil control circuits, the corresponding DTC sets.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC P0351 Ignition Coil 1 Control Circuit
    • DTC P0352 Ignition Coil 2 Control Circuit
    • DTC P0353 Ignition Coil 3 Control Circuit

Conditions for Running the DTC

    • The engine is cranking or running.
    • The DTCs run continuously when the above conditions are met.

Conditions for Setting the DTC

The PCM detects an incorrect voltage in an ignition coil control circuit for 90 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: Engine Controls Connector End Views or Powertrain Control Module Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

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 Testing for Intermittent Conditions and Poor Connections

3

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

Is the frequency within the specified range?

3-20 Hz

Go to Step 5

Go to Step 4

4

Measure the frequency between the ignition coil control circuit of the ICM and a good ground with a DMM.

Is the frequency within the specified range?

3-20 Hz

Go to Step 7

Go to Step 6

5

  1. Connect jumper wires from the harness connector of the ICM to the corresponding terminals of the ICM.
  2. Using the jumper wires, exchange the ignition coil control circuit of the affected ignition coil with a known good ignition coil control circuit.
  3. Exchange the spark plug wires of the corresponding coils.
  4. Install the fuel pump relay.
  5. Start the engine.
  6. Observe the current misfire data with the scan tool.

Does the cylinder misfire transfer with the suspected ignition coil control circuit?

--

Go to Step 8

Go to Step 10

6

Test the ignition coil control circuit of the ICM for the following conditions:

    • An open
    • A short to ground
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

7

Test the low reference circuit of the ICM for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

8

Test the ignition coil control circuit of the ICM for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 14

Go to Step 9

9

Test the low reference circuit of the ICM for high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

10

Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

11

Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

12

Replace the ICM and coil assembly. Refer to Ignition Coil Replacement .

Did you complete the replacement?

--

Go to Step 14

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13

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 14

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14

  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 15

15

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

System OK