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Home >> Hummer >> 2009 >> H3 Alpha >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 5.3L - DTC P0315 To DTC P064A >> DTC P0451-P0454 >> Circuit/System Description

Circuit/System Description

The fuel tank pressure (FTP) sensor measures air pressure or vacuum in the evaporative emission (EVAP) system. The engine control module (ECM) supplies a 5-volt reference and a low reference circuit to the FTP sensor. The FTP sensor signal voltage varies depending on EVAP system pressure or vacuum. The controller also uses this FTP signal to determine atmospheric pressure for use in the engine-off small leak test, DTC P0442. Before using this signal as an atmospheric reference it must first be re-zeroed.

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