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Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 1 (Displays And Gauges) >> Diagnostic Information and Procedures >> DTC P0071-P0074 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: B9 Ambient Air Temperature Sensor
  3. Test for less than 10 ohms between the test points: Low Reference circuit terminal B(or2) & Ground
    • If 10 ohms or greater 
    1. Disconnect the electrical connector: K20 Engine Control Module
    2. Test for less than 2 ohms between the test points: Low Reference circuit terminal B(or2) @ Component harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K20 Engine Control Module
    • Go to next step: If less than 10 ohms 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify the scan tool parameter: Ambient Air Temperature = Less than -34°C (-30°F)
    • If -34°C (-30°F) or warmer 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: Signal circuit terminal A(or1) @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K20 Engine Control Module
    • Go to next step: If -35°C (-31°F) or colder 
  6. Connect a 3 A fused jumper wire between the test points: Signal circuit terminal A(or1) & Low Reference circuit terminal B(or2)
  7. Verify the scan tool parameter: Ambient Air Temperature = Greater than 143°C (290°F)
    • If 143°C (290°F) or colder 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit @ Component harness & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K20 Engine Control Module
    • Go to next step: If 144°C (291°F) or warmer 
  8. Apply dielectric grease to connector terminals.
  9. Connect the component: B9 Ambient Air Temperature Sensor
  10. Operate the vehicle within the Conditions for Running the DTC.
  11. Verify the repair corrected the DTC/symptom.
    • If the repair did not correct the DTC/symptom 

      Test or replace the component: B9 Ambient Air Temperature Sensor

    • Go to next step: If the repair corrected the DTC/symptom 
  12. All OK.
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