For 1990-2009 cars

Refer to Engine Controls Schematics

#### Cell 21: Ignition Controls

Engine Controls Component Views
Information Sensors/Switches Description
Cell 21: Fuel Controls
Cell 21: Power, Ground, MIL, and DLC
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Ground Distribution 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 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 IC Module to switch spark advance to PCM control (IC mode). If the PCM detects an open in the IC circuit, DTC P1351 will set. The engine will start and may run in Bypass mode 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 first trip in which the diagnostic runs and fails.

• | If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control and illuminate the TRACTION OFF lamp.

• | 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 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

Check 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, 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 battery positive voltage while moving connectors and wiring harnesses related to the ICM. A change in voltage will indicate the location of the malfunction.

Refer to Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector Repairs in Wiring Systems.

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.

#### DTC P1351 - IC Circuit Open

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain OBD System Check performed? | -- | Go to Step 2 | Go to the Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn off the ignition switch.
2. Disconnect the PCM.
3. Connect J 39200 DMM between the IC and Reference Low Circuits.
4. Turn on the ignition switch.
5. Observe the resistance value on the J 39200 DMM.

Does the J 39200 DMM display a resistance below the specified value?

500ohms

Go to Step 4

Go to Step 3

3 |

1. Turn off the ignition switch.
2. Leave the PCM disconnected.
3. Disconnect the Ignition Control (IC) Module connector.
4. Test 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 Testing for Continuity , Intermittents and Poor Connections Diagnosis , Repairing Connector Terminals , and Connector 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 Module.
2. If a problem is found, repair as necessary. Refer to Testing for Continuity Intermittents and Poor Connections Diagnosis Repairing Connector Terminals and Connector Repairs 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 | Replace the PCM. Important: : Replacement PCM must be reprogrammed. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 8 | --
8 |

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

Does the scan tool indicate DTC 1351 failed this ignition?

--

Go to Step 2

System OK