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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 P0101CIRCUIT/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.
NOTE:

You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

  1. Verify the integrity of the entire air induction system by verifying that none of the conditions listed below exist:
    • Any damaged components
    • Improperly installed components
    • Collapsed, restricted, or damaged components
    • Loose clamps, cracks, or other damage
    • An air flow restriction
    • Restricted air filter
    • Splits, kinks, leaks, or improper connections at the vacuum hoses
    • Vacuum leaks at the intake manifold, MAP sensor, and throttle body
    • Water intrusion
    • Any snow or ice buildup, in cold climates
    • Contamination of the multifunction intake air sensor element
    • If a condition is found 

      Repair or replace component as appropriate.

    • Go to next step: If no condition is found 
  2. Ignition OFF. Disconnect the harness connector at the B75C Multifunction Intake Air Sensor.
  3. Test for less than 2 Ω between the ground circuit terminal 7 and ground.
    • If 2 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/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 2 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 signal circuit terminal 6 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 
    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 6 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 5 kHz
    • Duty Cycle switch to 50 % (Normal)
  9. Engine idling.
  10. Verify the scan tool MAF Sensor parameter is between 4, 950 - 5, 050 Hz.
    • If not between 4, 950 - 5, 050 Hz. 

      If not between 4, 950 - 5, 050 Hz, replace the K20 Engine Control Module.

    • Go to next step: If between 4, 950 - 5, 050 Hz. 
  11. Test or replace the B75C Multifunction Intake Air Sensor.
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.