Circuit/System Testing

2019 Chevrolet Trax Premier, AWDSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2018 Chevrolet Trax and 2018 Buick Encore. 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 B39 A/C Evaporator Temperature Sensor. It may take up to 10 min for all vehicle systems to power down.
  2. NOTE:

    The scan tool must be disconnected from the vehicle before performing the next test.

  3. Test for less than 10 Ω between the low reference circuit terminal B and ground.
    • If 10 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC 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 K33 HVAC Control Module.
    • Go to next step: If less than 10 Ω 
  4. Test for 4.8 - 5.2 V between the signal circuit terminal A and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module.
    2. Test for infinite resistance between the signal 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 signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K33 HVAC Control Module.
    • If greater than 5.2 V 
    1. Ignition OFF, disconnect the harness connector at the K33 HVAC Control Module, ignition ON.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K33 HVAC Control Module.
    • Go to next step: If between 4.8 - 5.2 V 
  5. Test or replace the B39 A/C Evaporator Temperature Sensor.
  6. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
  7. Verify the DTC does not set.
    • If the DTC sets 

      Replace the K33 HVAC Control Module.

    • Go to next step: If the DTC does not set 
  8. All OK
RENDER: 1.0x

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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.