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Home >> Cadillac >> 2016 >> ELR >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls And Fuel - 1.4L (LUU) - DTC P0449 To DTC 2635 And Diagnostic Information And Procedures >> Diagnostic Information and Procedures >> DTC P1101: Intake Air Flow System Performance >> Circuit/System Testing
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Circuit/System Testing

  1. Verify the following conditions do not exist:
    • A dirty, restricted, or deteriorating air filter element
    • A leaking, loose, or cracked PCV pipe or seal
    • A restricted or collapsed air intake duct
    • A misaligned, leaking, or damaged air intake duct
    • Any objects blocking the air inlet probe of the B75B Mass Air Flow/Intake Air Temperature sensor
    • Any contamination or debris on the sensing elements in the probe of the B75B Mass Air Flow/Intake Air Temperature sensor
    • A cracked, damaged, or leaking B75B Mass Air Flow/Intake Air Temperature sensor housing
    • Any water intrusion in the induction system
    • Any snow or ice build-up at the air cleaner or B75B Mass Air Flow/Intake Air Temperature sensor in cold climates
    • Any vacuum leak
    • A B74 Manifold Absolute Pressure sensor seal that is leaking, missing, or damaged
    • Q38 Throttle body for dirt, debris, and coking. Refer to Throttle Body Inspection and Cleaning .
    • A damaged Q38 throttle body blade or shaft
    • Missing, restricted, or leaking exhaust components. Refer to Symptoms - Engine Exhaust .
    • If a condition is found 

      Repair or replace component as appropriate.

    • If no condition is found 
  2. Vehicle OFF, disconnect the harness connector at the B75B Mass Air Flow/Intake Air Temperature sensor.
  3. Vehicle in Service Mode, test for 4.8-5.2 V between the signal circuit terminal 5 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.
    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 
  4. Verify that a test lamp illuminates between the ignition voltage circuit terminal 4 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 circuit.
    2. Test for less than 2 Ω in the ignition 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 circuit.
    2. Test for infinite resistance between the ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If Infinite, test all components connected to the ignition circuit, replace as necessary.
    • If a test lamp illuminates 
  5. Connect the test lamp between the MAF control circuit terminal 2 and the ignition voltage circuit terminal 4.
  6. Vehicle in Service Mode, command the MAF Sensor Supply Voltage Low Side Driver ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
    2. Test for infinite resistance between the low reference circuit terminal 2 and ground.
    • If less than infinite resistance, repair the short to ground on the circuit.
    • If infinite resistance, replace the K20 Engine Control Module.
    • If the test lamp is always OFF 
  7. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
  8. Ignition ON, Test for less than 1 V between the low reference circuit terminal 2 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 the test lamp turns ON and OFF 
  9. Vehicle OFF, connect the red lead of the J-38522  generator to the signal circuit terminal 5 at the harness connector. Connect the battery voltage supply to B+, and the black lead to ground.
  10. Set the J-38522  generator to the following specifications:
    • Signal switch to 5 V
    • Frequency switch to 5 KHz
    • Duty Cycle switch to Normal
    11. NOTE:

    The engine may run rough and stall.

  11. Vehicle ON, engine running, observe the scan tool MAF Sensor Hz parameter. The parameter should be between 4, 950 and 5, 025 Hz.
    • If not within specified range 

      Replace the K20 Engine Control Module

    • If within specified range 
  12. Test or replace the B75B Mass Air Flow/Intake Air Temperature sensor.
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