GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The ignition control (IC) module has independent power and ground circuits. The circuits between the IC module and the powertrain control module (PCM) consist of the following circuits:

    â€¢ The IC timing signal
    â€¢ The IC timing control
    â€¢ The low-resolution engine speed signal
    â€¢ A low reference signal

The ignition control (IC) module sends 3x signals to the powertrain control module (PCM). The IC module controls the timing advance during engine cranking. The timing advance changes to PCM control after the following actions:

    â€¢ The PCM receives the second 3x signal.
    â€¢ The PCM applies 5 volts to the IC timing signal circuit.
    â€¢ The timing advance switches to PCM control.

Conditions for Running the DTC

    â€¢ Engine speed is more than 600 RPM.
    â€¢ No DTC P1351 set.

Conditions for Setting the DTC

    â€¢ The PCM does not monitor IC pulses while IC mode spark advance is commanded.
    â€¢ The condition is present for 300 3X reference periods, 100 crankshaft revolutions.

Action Taken When the DTC Sets

    â€¢ The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    â€¢ 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

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

Test Description

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

  1. This step determines if DTC P1362 is also set.

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

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC information for DTC P1362 in the PCM.

Does the scan tool indicate that DTC P1362 is current?

--

Go to Step 6

Go to Step 3

3

  1. Observe the Freeze Frame/Failure Records data 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 as specified in the supporting text or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

--

Go to Step 4

Go to Intermittent Conditions

4

  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Turn ON the ignition.
  4. Probe the IC timing control circuit with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 14

5

  1. Turn OFF the ignition.
  2. Leave the PCM disconnected.
  3. Disconnect the ignition control module connector.
  4. Turn ON the ignition.
  5. Probe the IC timing control circuit with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 13

6

  1. Turn OFF the ignition.
  2. Disconnect the PCM.
  3. Disconnect the ignition control module.
  4. Probe the IC timing control circuit at the PCM with a test lamp connected to battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 7

7

  1. Leave the ignition OFF.
  2. Leave the PCM disconnected.
  3. Leave the ignition control module disconnected.
  4. Probe the IC timing signal circuit with a test lamp connected to battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 12

Go to Step 8

8

  1. Leave the ignition OFF.
  2. Leave the PCM disconnected.
  3. Leave the ignition control module disconnected.
  4. Test for a short between the IC timing control and IC timing signal circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 9

9

  1. Leave the ignition OFF.
  2. Reconnect the ignition control module.
  3. Leave the PCM disconnected.
  4. Turn ON the ignition.
  5. Using the DMM, observe the resistance between the IC timing control circuit and a known good ground while probing the IC timing signal circuit with a test lamp connected to battery positive voltage.

Does the resistance toggle between the two indicated ranges?

100-600 ohms to 6,000-10,000 ohms

Go to Step 14

Go to Step 13

10

Repair the short to voltage in the IC timing control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

--

11

Repair the short to ground in the IC timing control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

--

12

Repair the short to ground in the IC timing signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

--

13

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

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  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 16

Go to Step 3

16

With a scan tool, 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