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Home >> GMC >> 2018 >> Terrain Denali, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 12 (Engine Controls And Fuel - 1.5L (LYX) - Diagnostic Information And Procedures (P0010 - P034B)) >> Diagnostic Information And Procedures >> DTC P00F4, P00F5, P00F6: Intake Air Humidity Sensor >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
NOTE:

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

  1. Ignition Off, disconnect the harness connector at the B75C Multifunction Intake Air sensor.
  2. Test for less than 2 Ω between the ground 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.
    • Go to next step: If less than 2 Ω 
  3. 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.
    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.
    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.
      • If infinite resistance, test all components connected to the ignition circuit, replace as necessary.
    • Go to next step: If a test lamp illuminates 
  4. Test for greater than 10.5 V between the humidity signal circuit terminal 8 and ground.
    • If 10.5 V or less 
    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 10.5 V 
  5. Determine if EL-38522-A  or equivalent is available.
    • If EL-38522-A, 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, or equivalent is available 
  6. Ignition Off, connect the leads of the EL-38522-A  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+
  7. Set the EL-38522-A  to the specifications listed below:
    • Signal switch to 5 V
    • Frequency switch to 250 Hz
    • Duty Cycle switch to 50 % (Normal)
  8. Ignition On, verify the scan tool Intake Air Humidity parameter is between 45 - 55 %.
    • If not within the specified range 

      Replace the K20 Engine Control Module.

    • Go to next step: If within the specified range 
  9. Test or replace the B75C Multifunction Intake Air sensor.
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