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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 P0446 >> Circuit/System Testing

Circuit/System Testing

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NOTE:

Perform the Circuit/System Verification before proceeding with the Circuit/System Testing.

Restriction

  1. With the engine running, the EVAP vent solenoid valve open, and the EVAP purge solenoid valve commanded to 100 %, the fuel tank vacuum should not increase to greater than -15 mm Hg (-8 in H2O).
    • If greater than the specified value, isolate the restriction by disconnecting one component at a time while the EVAP purge solenoid valve is commanded to 100 % and the vent valve is open.
  2. Using the scan tool decrease the canister purge duty cycle from 100 % to 0 %. The vacuum should decrease to near zero.
    • If not the specified value or appears to decrease too slowly, inspect the components in the EVAP vent system for a restriction.

Fuel Tank Pressure Sensor

  1. Ignition OFF, disconnect the harness connector at the B150 Fuel Tank Pressure Sensor.
  2. Ignition OFF, all vehicle systems OFF, this may take up to 2 min, test for less than 5 Ω between the low reference circuit terminal and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the B150 Fuel Tank Pressure Sensor.
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