GM Service Manual Online
For 1990-2009 cars only

Object Number: 577084  Size: LF
Engine Controls Components
Power, Ground, CMP, CKP 24X, CKP 7X, KS, and ICM
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The ignition control (IC) module sends signals that the powertrain control module (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 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 it has 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 ICM controlling spark timing.

Conditions for Running the DTC

    •  Engine speed is more than 600 RPM.
    •  No DTC P1351 set.

Conditions for Setting the DTC

    •  The PCM does not monitor IC pulses while IC mode spark advance is commanded.
    •  The condition 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.

Test Description

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

  1. This step ensures that the replacement PCM, which utilizes an electrically erasable programmable read only memory (EEPROM), is programmed when installed.

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

Is DTC P1362 set also?

--

Go to Step 6

Go to Step 3

3

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

Did the test lamp illuminate?

--

Go to Step 4

Go to Step 13

4

  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 circuit with a test lamp to ground.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 12

5

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

Did you complete the repair?

--

Go to Step 14

--

6

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

Does the test lamp illuminate?

--

Go to Step 7

Go to Step 8

7

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

Did you complete the repair?

--

Go to Step 14

--

8

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

Does the test lamp illuminate?

--

Go to Step 9

Go to Step 10

9

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

Did you complete the repair?

--

Go to Step 14

--

10

  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 and BYPASS circuits. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

11

  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 voltage between the IC and Reference Low circuits while probing the BYPASS circuit with a test lamp to battery positive voltage.

Does the voltage toggle between the two indicated ranges?

20-40 mV

150-250 mV

Go to Step 13

Go to Step 12

12

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

Did you complete the replacement?

--

Go to Step 14

--

13

Important: The replacement PCM must be reprogrammed.

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

Did you complete the replacement?

--

Go to Step 14

--

14

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

Does the scan tool indicate DTC P1361 failed this ignition?

--

Go to Step 2

System OK