GM Service Manual Online
For 1990-2009 cars only

Refer to Engine Controls Schematics .

Circuit Description

The ignition control (IC) module sends signals that the PCM requires for fuel control and spark advance calculations. At the start of engine crank the IC module controls spark advance. When the second 3X reference pulse is recognized by the PCM, the PCM applies 5.0 volts to the Bypass circuit. The 5.0 volts on the Bypass circuit commands the IC module to switch spark advance to PCM control. At this time, the IC module will remove the ground that was applied to the IC circuit. When the IC pulses are not grounded, the IC Module can use the IC pulses to control spark advance. A short in the IC circuit or an open or short to ground in the Bypass circuit will cause the PCM to set DTC P1361. The engine may be started but will run with the IC module controlling spark timing.

Conditions for Running the DTC

    •  Engine speed more than 600 RPM.
    • DTC P1351 is not set.

Conditions for Setting the DTC

    •  The PCM does not monitor IC pulses while IC mode spark advance is commanded.
    •  The conditions is present for 300 3X reference periods (100 crankshaft revolutions).

Action Taken When the DTC Sets

    • The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
    • The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

Conditions for Clearing the MIL/DTC

    • The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
    • The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
    • The DTC can be cleared by using a scan tool.

Diagnostic Aids

Inspect for the following conditions:

Many situations may lead to an intermittent condition. Perform each inspection or test as directed.

Important: :  Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.

    • Loose terminal connection
       -  Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
       -  Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair.
    • Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.
    •  Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair.

If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.

Step

Action

Values

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 engine and let idle for 2 minutes.
  2. Observe DTCs.

Did DTC P1361 set?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn the ignition OFF.
  2. Disconnect the PCM.
  3. Install a test lamp between battery positive voltage and the bypass circuit at the PCM harness connector.

Did the test lamp illuminate?

--

Go to Step 8

Go to Step 4

4

  1. Turn the ignition on.
  2. With the test lamp installed between battery positive voltage and the bypass circuit, measure the resistance between the IC circuit and the reference low circuit using a DMM.

Is the resistance more than the specified value?

6Kohms (6000ohms)

Go to Step 12

Go to Step 5

5

  1. Turn the ignition OFF.
  2. Probe the IC circuit with a test lamp to battery positive voltage.

Did the test lamp illuminate?

--

Go to Step 10

Go to Step 6

6

  1. Test the bypass circuit for an open.
  2. Refer to Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 15

Go to Step 7

7

  1. Test the bypass circuit for a poor terminal connection at the IC Module.
  2. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 14

8

  1. Turn OFF the ignition.
  2. Disconnect the ignition control (IC) module.
  3. Turn ON the ignition.
  4. Observe test lamp connected between the bypass circuit and battery positive voltage.

Did the test lamp illuminate?

--

Go to Step 11

Go to Step 14

9

  1. Turn the ignition OFF.
  2. Disconnect the ignition control (IC) module.
  3. Turn the ignition on, check the IC circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

10

Locate and repair short to ground in the IC circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

--

11

Locate and repair short to ground in the bypass circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 15

--

12

Test the Bypass circuit for a poor terminal connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 15

Go to Step 13

13

Important: :  The replacement PCM must be programmed.

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

Did you complete the replacement?

--

Go to Step 15

--

14

Replace the Ignition Control Module. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

--

Go to Step 15

--

15

  1. Review and record scan tool Fail Records data.
  2. Clear DTCs.
  3. Operate vehicle within Fail Records conditions as noted.
  4. Using a scan tool, monitor Specific DTC info for DTC P1361.

Does scan tool indicate DTC P1361 failed?

--

Go to Step 2

System OK