P0351

CIRCUIT DESCRIPTION
The enhanced ignition system uses the Crankshaft Position (CKP) sensor in order to provide a timing input to the control module. Ignition Control (IC) spark timing for each cylinder is based on this input. The control module provides the ignition timing signal to the Ignition Control Module (ICM) to control the ignition coil. Each timing pulse detected by the ICM allows it to energize the ignition coil. A large secondary ignition voltage is induced in the secondary coil by the primary coil. This high voltage is switched to the correct spark plug by the distributor. This Diagnostic Trouble Code (DTC) will set if the Powertrain Control Module (PCM) detects an unusually high or low voltage on the ignition timing signal circuit.

CONDITIONS FOR RUNNING THE DTC
^ The ignition control is enabled.
^ The engine speed is less than 250 RPM.

CONDITIONS FOR SETTING THE DTC
The ignition control voltage is not within the specified range of 0.04-4.9 volts.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Use a scan tool in order to clear the MIL and the DTC.

TEST DESCRIPTION

Steps 1-4:

Steps 5-17:

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the DTC is an intermittent.
3. This step checks if the IC timing signal from the PCM is available at the ignition control module.