OBD Operation Summary for Fiesta - MotorCraftService.com

NVLD II OverviewThe NVLD II evaporative system monitor consists of an NVLD II module, the Canister Purge Solenoid (CPS) andsoftware in the ECM that enables/disables the monitor, determines fault status and manages fault code storage, Mode$06 data, Mode $09 data, etc.The NVLD II monitor performs a small (0.020“) leak check during engine off and a large leak check during enginerunning. The NVLD II module incorporates a pressure switch and temperature sensor so the monitor also includes acomplete series of auxiliary checks to confirm the integrity of the mechanical and electrical components that make up theentire evap monitoring system. The NVLD II module is powered after the ignition key is turned off so that the entire ECMdoes not have to be powered to perform the engine-off small leak check. This saves a considerable amount of currentdraw from the battery.The following functions are managed by the software in the ECM:- 0.020” small leak detection enablement and fault decision (engine off)- Large leak/fuel cap off detection enablement and fault decision (engine running)- Canister purge solenoid (CPS) (electrical/wiring and mechanical rationality)- NVLD II communications (protocol check and electrical/wiring)The following functions are managed by the NVLD II module- NVLD II pressure switch (electrical/wiring and mechanical rationality check)- NVLD II temperature sensor (rationality and out of range check)- NVLD II timer (rationality check)CONTINENTAL REVISED: SEPTEMBER 17, 2010 PAGE 16 OF 111