P1371

Circuit Description

This diagnostic test checks for too few 4X reference pulses between CAM pulses. The PCM checks to see if there are 48 24X reference pulses between CAM pulses, and if there are, the PCM assumes it is receiving valid cam pulses. Therefore, if the PCM sees less than eight 4X reference pulses between cam pulses, it sets DTC P1371, because the 4X reference signal must be faulty.

Conditions for Running the DTC

^ DTC P1376 not set.
^ Engine speed higher than 496 RPM.
^ At least 7 CAM pulses received since key ON.
^ At least one CAM pulse received in the last 0.25 second.
^ 48 24X reference pulses received between CAM pulses.

Conditions for Setting the DTC

The PCM has received less than 8 4X reference pulses between CAM pulses.

Action Taken When the DTC Sets

^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.
^ Use a scan tool to clear DTCs.
^ Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids

An intermittent open or short to ground in CKT 430 may set this DTC, check terminals carefully.

Test Description

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

2. Diagnose DTCs P0322 or P1320 first because those problems can cause P1371 to set.
3. Checking for possible cause of noise (missing 4X pulses) on the Fuel Control (4X) circuit.