Circuit Description
The ignition control module (ICM) sends the signals that the powertrain control module (PCM) requires for fuel control and spark advance calculations. At the start of engine crank, the ICM controls the 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 ICM to switch the 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 the ICM controlling the 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:
| • | A poor connection at the PCM or the ICM. Inspect harness connectors for the following conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems: |
| - | Backed-out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal-to-wire connection |
| • | A 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 (DMM) connected between the IC circuit and B+ voltage while moving the connectors and the wiring harnesses related to the ICM. A change in the voltage indicates 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.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 |
Is the resistance less than the specified value? | 500 ohms | ||
3 |
Was a problem found? | -- | ||
4 |
Was a problem found? | -- | ||
5 |
Was a problem found? | -- | ||
6 | Replace the ignition control module. Is the action complete? | -- | -- | |
7 |
Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |
8 |
Does the scan tool indicate DTC P1351 failed this ignition? | -- | System OK |
