Circuit/System Testing

2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A7 Fuel Pump and Level Sensor. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the low reference circuit terminal 2 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis Control Module.
    2. Test for less than 2 Ω in the low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K38 Chassis Control Module.
    • Go to next step: If less than 10 Ω 
  3. Connect a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
  4. Ignition ON.
  5. Verify the test lamp turns ON and OFF when commanding the fuel pump ON and OFF using the scan tool ECM fuel pump enable control function.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis Control Module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K38 Chassis Control Module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K38 Chassis Control Module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K38 Chassis Control Module.
    • Go to next step: If the test lamp turns ON and OFF 
  6. Replace the A7 Fuel Pump and Level Sensor.
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When to See a Mechanic

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

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