Refer to
Ignition Control and the Knock Sensor System
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). An open in the IC circuit or a short to voltage in the Bypass circuit at start-up will cause the PCM to monitor IC pulses during crank, when the ICM should be grounding the IC circuit. This condition will set DTC P1350. The engine may be started but will run on Bypass mode timing.
Conditions for Setting the DTC
| • | The PCM monitors IC pulses during crank while Bypass mode spark advance is commanded. |
| • | Engine speed less than 450 rpm. |
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
Check for the following conditions:
| • | Poor connection at 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 voltmeter 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 fault. |
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 System Check performed? | -- | Go to Powertrain OBD System Check | |
2 |
Did DTC P1350 set? | -- | Refer to Diagnostic Aids | |
3 |
Is resistance less than the specified value? | 300 ohms | ||
4 |
Was a problem found? | -- | ||
5 |
Was a problem found? | -- | ||
6 |
Was a problem found? | -- | ||
7 | Replace the PCM. Important: Replacement PCM must be programmed. Refer to PCM Replacement/Programming. Is action complete? | -- | -- | |
8 |
Was a problem found? | -- | ||
9 | Replace the ignition control module. Is action complete? | -- | -- | |
10 |
Does scan tool indicate DTC P1350 failed? | -- | Repair complete |
