Circuit/System Testing

2011 GMC Savana Special 4.8 ASECTION Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
  1. Install the CH-48027 to the fuel system service port on the right front side of the engine. Verify the CH-48027 displays 0 in Hg.
  2. Ignition OFF, disconnect the harness connector at the B181 fuel filter pressure switch.
  3. Test for less than 10 Ξ© between the B181 fuel filter pressure switch terminal A and terminal B.
    • If greater than the specified value, replace the B181 fuel filter pressure switch.
  4. Test for less than 5 Ξ© between the low reference circuit terminal B and ground.
    • If greater than the specified value, repair the open or high resistance in the low reference circuit.
  5. Ignition ON, verify the scan tool Fuel Pressure Switch parameter displays High Pressure.
    • If other than the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the K20 engine control module.
  6. Install a 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Fuel Filer Pressure Switch parameter displays Normal.
    • If other than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
    • If all circuits test normal, refer to Diagnostic Aids above.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.