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HOMESERVICE MANUALSCHEVROLET2020EXPRESS 2500 LS, 2.8L ENG VIN 1REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 102 (ENGINE CONTROLS AND FUEL - 6.0L (L96 LC8) - DIAGNOSTIC INFORMATION AND PROCEDURES (1 OF 2))DIAGNOSTIC INFORMATION AND PROCEDURESDTC P00F4-P00F6CIRCUIT/SYSTEM TESTING
2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1

Circuit/System Testing

2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1SECTION 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.
  1. Ignition OFF and all systems OFF, it may take up to for 2 min for all vehicle systems to power down. Disconnect the harness connector at the B75C Multifunction Intake Air Sensor.
  2. Test for less than 2 Ω between the low reference circuit terminal 3 and ground.
    • If 5 Ω or greater 
    1. Disconnect the harness connector at the K20 Engine 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 or high resistance in the circuit.
      • If less than 2 Ω replace the K20 Engine Control Module.
    • Go to next step: If less than 5 Ω 
  3. Test for less than 5 Ω between the ground circuit terminal 7 and ground.
    • If 5 Ω or greater 
    1. Disconnect the sensor chassis ground.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open or high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • Go to next step: If less than 5 Ω 
  4. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 5 and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition OFF, remove the test lamp and remove the fuse for the ignition voltage circuit.
    2. Test for less than 2 Ω in the ignition voltage circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF, remove the test lamp and remove the fuse for the ignition voltage circuit.
    2. Test for infinite resistance between the ignition voltage 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 greater than 2 Ω between the ignition voltage circuit terminal 5 and ground.
      • If less than 2 Ω, repair the short to ground on the circuit.
      • If greater than 2 Ω, test all the components connected to the circuit and repair or replace as necessary.
    • Go to next step: If a test lamp illuminates 
  5. Ignition ON, test for 4. 8 - 5. 2 V between the humidity signal circuit terminal 8 and ground.
    • If less than 4. 8 V 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine 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 K20 Engine Control Module.
    • If greater than 5. 2 V 
      NOTE:

      If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.

    1. Ignition OFF, disconnect the harness connector at the K20 Engine 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 K20 Engine Control Module.
    • Go to next step: If between 4. 8 - 5. 2 V 
  6. Determine if EL-38522-A  Variable Signal Generator or equivalent is available.
    • EL-38522-A, Variable Signal Generator; or equivalent is not available 
    1. Test or replace the B75C Multifunction Intake Air Sensor.
    2. 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.
    3. Verify the DTC does not set.
      • If the DTC sets 

        Replace the K20 Engine Control Module.

      • Go to next step: If no DTCs set 
    4. All OK.
    • Go to next step: EL-38522-A, Variable Signal Generator; or equivalent is available 
  7. Ignition OFF, connect the leads of the EL-38522-A  Variable Signal Generator as listed below:
    • Red lead to the signal circuit terminal 8 at the harness connector
    • Black leads to ground
    • Battery voltage supply lead to B+
  8. Set the EL-38522-A  Variable Signal Generator to the specifications listed below:
    • Signal switch to 5 V
    • Frequency switch to 250 Hz
    • Duty Cycle switch to 50 % (Normal)
  9. Ignition ON.
  10. Verify the scan tool Intake Air Humidity Sensor parameter is between 45 - 55 %.
    • If not between 45 - 55 %. 

      Replace the K20 Engine Control Module.

    • Go to next step: If between 45 - 55 %. 
  11. Test or replace the B75C Multifunction Intake Air Sensor.
RENDER: 1.0x

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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.