GM Service Manual Online
For 1990-2009 cars only

Object Number: 517307  Size: MF
Engine Controls Components
CMP, CKP and ICM
OBD II Symbol Description Notice
Handling ESD Sensitive Parts 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, commanding the IC module to switch spark advance to PCM control . If the PCM detects an open in the IC circuit, DTC P1351 will set. The engine will start and may run with IC module controlling spark timing.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

    • The PCM detects an open in the IC circuit.
    • 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 and Failure Records data.

Conditions for Clearing the MIL/DTC

    • The PCM will turn OFF the MIL 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.

Diagnostic Aids

Inspect for the following conditions:

    • Poor connection at the PCM or IC module--Inspect harness connectors for:
       - Backed out terminals
       - Improper mating
       - Broken locks
       - Improperly formed or damaged terminals
       - Poor terminal to wire connection
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems .
    • Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the IC module, turn the ignition ON and observe a DMM connected between the IC circuit and battery positive voltage while moving connectors and wiring harnesses related to the IC module. A change in voltage will indicate the location of the malfunction. Refer to Wiring Repairs in Wiring Systems .

Reviewing the Failure 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.

DTC P1351 - IC Circuit Open

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. Turn OFF the ignition switch.
  2. Disconnect the PCM.
  3. Connect a DMM between the IC and reference low circuits.
  4. Turn ON the ignition switch.
  5. Observe the resistance value on the DMM.

Does the DMM display a resistance below the specified value?

500 ohms

Go to Step 4

Go to Step 3

3

  1. Turn OFF the ignition switch.
  2. Leave the PCM disconnected.
  3. Disconnect the IC module connector.
  4. Check for an open in the IC circuit.
  5. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 8

Go to Step 5

4

  1. Test for poor terminal connections at the PCM.
  2. If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

--

Go to Step 8

Go to Step 7

5

  1. Test for poor terminal connections at the IC m odule.
  2. If a problem is found, repair as necessary. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Was a problem found?

--

Go to Step 8

Go to Step 6

6

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

Is the action complete?

--

Go to Step 8

--

7

Important: : The replacement PCM must be programmed.

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

Is the action complete?

--

Go to Step 8

--

8

  1. Review and record the scan tool Failure Records data.
  2. Clear the DTCs.
  3. Operate the vehicle within the Failure Records conditions.
  4. Using the scan tool, monitor Specific DTC info for DTC P1351.

Does the scan tool indicate DTC P1351 failed this ignition?

--

Go to Step 2

System OK