In order to detect engine misfire at higher enginespeeds, the Engine Control Module (ECM) must know ofany variation between the crankshaft sensor pulses.Most variations are due to the machining of the crankshaftreluctor wheel. However, other sources of variationare also possible. A Crankshaft Position (CKP) systemvariation learning procedure must be performed anytime a change is made to the crankshaft sensor tocrankshaft relationship of if the ECM is replaced or reprogrammed.The ECM measures the variations andthen calculates compensation factors needed to enablethe ECM to accurately detect engine misfire at allspeeds and loads. A scan tool must be used to commandthe ECM to learn these variations. If for any reasonthe ECM is unable to learn these variations or theyare out of an acceptable range, the ECM will set DiagnosticTrouble Code (DTC). An ECM that has nothad the CKP system variation learning procedure performeddue to replacement or reprogramming will alsoset a DTC.

DTC P0315 will only set if the ECM has not learned the CKP system variation. The ECM only needs to learn this variation once per life cycle of the vehicle unless the crank sensor to crankshaft relationship is disturbed. Removing a part is considered a disturbance. A fully warmed engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed that ignition cycle.

If the engine cuts out before the specified learn procedure engine speed or at normal fuel cutoff rpm, the ECM is not in the learn procedure mode.

The number(s) below refer to step(s) on the diagnostic table.

The Engine Control Module (ECM) identifies engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operating over a rough road. The ECM receives rough road signal by gravity sensing rough road (G) sensor or Electronic Brake Control Module (EBCM) if equipped with the Anti-Lock Brake System (ABS). The ABS can detect if the vehicle is on the rough surface based on wheel acceleration/deceleration data supplied by each wheel speed sensor. This information sent to the ECM by EBCM through serial data line. The G sensor is vertical low g-acceleration sensor. By sensing vertical acceleration caused by bumps or portholes in the road, the ECM determine if the changes in crankshaft speed are due to engine misfire or are driveline induced. If the ECM can not receive any of those signal, a historic Diagnostic Trouble Code (DTC) will be stored.

An open signal circuit of G sensor or open serial data line between the ECM and the EBCM will be the cause of this DTC.

The Knock Sensor (KS) system is used to detect engine detonation, allowing the Engine Control Module (ECM) to retard the ignition control spark timing based on the KS signal being received. The KS produces an AC signal so that under a no-knock condition the signal on the KS circuit measures about 0.007 volts AC. The KS signal's amplitude and frequency depend upon the amount of knock being experienced. The ECM contains a nonreplaceable knock filter module called a Digitally Controlled Signal-to-Noise Enhancement Filter (DSNEF) module. This filter module in the ECM determines whether or not knock is occurring by comparing the signal level on the KS circuit with the voltage level on the noise channel. The noise channel allows the ECM to reject any false knock signal by knowing the amount of normal engine mechanical noise present. Normal engine noise varies depending on engine speed and load. When the ECM determines that an abnormally low noise channel voltage level is being experienced, Diagnostic Trouble Code (DTC) will set.

Check and correct any abnormal engine noise before using the diagnostic table.

Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for the following conditions:

Number(s) below refer to the step number(s) on the Diagnostic Table.

The Knock Sensor (KS) system is used to detect engine detonation, allowing the Engine Control Module (ECM) to retard the ignition control spark timing based on the KS signal being received. The KS produces an AC signal so that under a no-knock condition the signal on the KS circuit measures about 0.007 volts AC. The KS signal's amplitude and frequency depend upon the amount of knock being experienced. The ECM monitors the KS signal and can diagnose the KS and circuitry.

Check and correct any abnormal engine noise before using the diagnostic table.

Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for the following conditions:

Number(s) below refer to the step number(s) on the Diagnostic Table.

The 58X reference signal is produced by the Crankshaft Position (CKP) sensor. During one crankshaft revolution, 58 crankshaft pulses will be produced. The Engine Control Module (ECM) uses the 58X reference signal to calculate engine rpm and CKP. The ECM constantly monitors the number of pulses on the 58X reference circuit and compares them to the number of Camshaft Position (CMP) signal pulses being received. If the ECM does not receive any 58X reference pulses on the 58X reference circuit while cranking, Diagnostic Trouble Code (DTC) will set.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a wire broken inside the insulation. Check for:

The 58X reference signal is produced by the Crankshaft Position (CKP) sensor. During one crankshaft revolution, 58 crankshaft pulses will be produced. The Engine Control Module (ECM) uses the 58X reference signal to calculate engine rpm and CKP. The ECM constantly monitors the number of pulses on the 58X reference circuit and compares them to the number of Camshaft Position (CMP) signal pulses being received. If the ECM receives and incorrect number of pulses on the 58X reference circuit, Diagnostic Trouble Code (DTC) P0336 will set.

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a wire broken inside the insulation. Check for: