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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 508 (Engine Controls/Fuel - 5.3L, 6.0L, 6.2L - DTC P0420 To DTC P3449 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P2636 >> Circuit/System Description

Circuit/System Description

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The secondary fuel pump is located in the rear fuel tank. The secondary fuel pump is powered by a secondary fuel pump relay. Fuel is transferred from the rear fuel tank to the front fuel tank in order to ensure all of the usable fuel volume is available to the primary fuel pump. The secondary fuel pump relay is controlled by the engine control module (ECM). If the engine is running the secondary fuel pump is normally ON.