GM Service Manual Online
For 1990-2009 cars only

Object Number: 248222  Size: LF
Engine Controls Components
Ignition System, Knock Sensor
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Ignition Control Module (ICM) sends signals that the PCM requires for fuel control and spark advance calculations. At the start of engine crank, the ICM controls spark advance (Bypass mode.) When the second 3X reference pulse is recognized by the PCM, the PCM applies 5 volts to the Bypass circuit, commanding the ICM to switch spark advance to PCM control (IC mode). If the PCM detects a short to voltage in the IC circuit, DTC P1361will set. A short to ground in the IC circuit or Bypass circuit will cause both DTC P1361 and DTC P1362 to set. The engine will start and may run in Bypass mode timing.

Condition for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • The PCM detects a short to voltage in the IC circuit.
    • The conditions is present for 300 3X reference periods (100 crankshaft revolutions).

Action Taken When the DTC Sets

    • The PCM will illuminate the 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 and Fail Records data.

Conditions for Clearing the MIL/DTC

    • The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been 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 the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for the following conditions:

    • Poor connection at the PCM.
        Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
    • Damaged harness.
        Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the ICM, turn the ignition ON and observe a digital multimeter connected between the IC circuit and B+ while moving connectors and wiring harnesses related to the ICM. A change in voltage will indicate the location of the malfunction.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Start the 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 light between battery positive voltage and the bypass circuit at the PCM harness connector.

Is the test light on?

--

Go to Step 8

Go to Step 4

4

  1. Turn the ignition on.
  2. With the test light 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 greater than the specified value?

6Kohms (6,000ohms)

Go to Step 12

Go to Step 5

5

  1. Turn the ignition off.
  2. Disconnect the ignition control module connector.
  3. Probe IC circuit with a test light to battery positive voltage.

Is Test light on?

--

Go to Step 10

Go to Step 6

6

  1. Check the bypass circuit for an open.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 15

Go to Step 7

7

  1. Check the bypass circuit for a poor terminal connection at the ignition control module.
  2. If a problem is found, replace faulty terminal. Refer to Repairing Connector Terminals in Wiring Systems.

Was a problem found?

--

Go to Step 15

Go to Step 14

8

  1. Turn the ignition off.
  2. Disconnect the ignition control module connector.
  3. Turn the ignition on.
  4. Observe test light connected between the bypass circuit and battery positive voltage.

Is the test light on?

--

Go to Step 11

Go to Step 14

9

  1. Turn the ignition off.
  2. Disconnect the Ignition Control Module.
  3. Turn the ignition on.
  4. Check the IC circuit for a short to voltage.
  5. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 15

Go to Step 13

10

Locate and repair short to ground in the IC circuit. Refer to Testing for Short to Ground in Wiring Systems.

Is the action complete?

--

Go to Step 15

--

11

Locate and repair short to ground in the bypass circuit. Refer to Testing for Short to Ground in Wiring Systems.

Is the action complete?

--

Go to Step 15

--

12

  1. Check the Bypass circuit for a poor terminal connection at the PCM.
  2. If a problem is found, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Was a problem found?

--

Go to Step 15

Go to Step 13

13

Replace the PCM.

Important: :  Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 15

--

14

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

Is the action complete?

--

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

Repair complete