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HOMESERVICE MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 130 (ENGINE CONTROLS/FUEL - 1.4L (LUV) - DTC P0300 TO DTC P2635 & SYMPTOMS)DIAGNOSTIC INFORMATION AND PROCEDURESDTC P2635 (CHASSIS CONTROL MODULE)CIRCUIT/SYSTEM TESTING
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol

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.
NOTE:

Do not replace the chassis control module based on a history DTC P2635. The DTC P2635 may be stored but that does not indicate a failure of the chassis control module. Refer to Strategy Based Diagnosis for further history DTC diagnostics.

  1. Ignition ON.
  2. Verify DTCs P018B, P018C, P018D, P0231, P0232 or P023F are not set.
    • Go to next step: If none of the DTCs are set 
  3. Verify the proper fuel system pressure. Perform the fuel system pressure test, refer to Fuel System Diagnosis .
    • If the fuel system pressure test is not normal 

      Replace the A7 Fuel Pump and Level Sensor Assembly.

    • Go to next step: If the fuel system pressure test is normal 
  4. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the A7 Fuel Pump and Level Sensor Assembly. It may take up to 2 minutes for all vehicle systems to power down.
  5. 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 
  6. Connect a test lamp between the control circuit terminal 1 and the low reference circuit terminal 2.
  7. Ignition ON.
  8. 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 
  9. All OK.
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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.