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Home >> Chevrolet >> 2015 >> Cruze LT, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls And Fuel - 1.8L (LUW, LWE) - DTC P0010 To DTC P0442) >> Diagnostic Information and Procedures >> DTC P00F4-P00F6: Intake Air Humidity Sensor Circuit >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
NOTE: You must perform Circuit/System Verification  before proceeding with Circuit/System Testing.
  1. Ignition OFF and all vehicle systems OFF, disconnect the B75C Multifunction Intake Air sensor. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 2 Ω between the low reference circuit terminal 7 and ground.
    • If 2 Ω or greater 
    1. Ignition OFF, 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.
    • If less than 2 Ω 
  3. Ignition OFF, all vehicle systems OFF, test for less than 2 Ω between the ground circuit terminal 4 and ground.
    • If 2 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
    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.
    • If less than 2 Ω 
  4. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 2 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.
      • 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.
      NOTE: If the 5 V reference circuit is shorted to a voltage the engine control module or the sensor may be damaged.
    2. Ignition ON, test for less than 1 V between the 5 V reference 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.
    • If between 4.8-5.2 V 
  5. Ignition ON, test for 4.8-5.2 V between the humidity signal circuit terminal 1 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.
      • 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.
      NOTE: If the signal circuit is shorted to a voltage the engine control module or the sensor may be damaged.
    2. Ignition ON, 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.
    • If between 4.8-5.2 V 
  6. Determine if EL-38522-A  Variable Signal Generator or equivalent is available.
    • If EL-38522-A, Variable Signal Generator; or equivalent is not available 
    1. Replace the K20 Engine Control Module.
    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 

        Refer to step  10.

      • If no DTCs set 
    4. Refer to step  11.
    • If 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 follows:
    • Red lead to the signal circuit terminal 1 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 following specifications.
    • Signal switch to 5 V
    • Frequency switch to 250 Hz
    • Duty Cycle switch to 50% (Normal)
  9. Ignition ON, verify the scan tool Intake Air Humidity parameter is between 45-55%.
    • If not between 45-55% 

      Replace the K20 Engine Control Module.

    • If between 45-55% 
  10. Test or replace the B75C Multifunction Intake Air sensor.
  11. All OK.
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