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Home >> Chevrolet >> 2016 >> City Express LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 2.0L >> Diagnostic Information And Procedures >> DTC P0111, P0127: Intake Air Temperature (IAT) Sensor >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF and all vehicle systems OFF, disconnect the Multifunction Intake Air sensor. It may take up to 2 min for all vehicle systems to power down.
  2. Test for less than 2 Ω between the low reference circuit terminal 5 and ground.
    • If 2 Ω or greater 
    1. Ignition OFF, disconnect the harness connector at the 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 Engine Control Module.
    • Go to next step: If less than 2 Ω 
  3. Ignition ON, test for 4.8 - 5.2 V between the intake air temperature sensor signal circuit terminal 6 and ground.
    • If less than 4.8 V 
    1. Ignition OFF, disconnect the harness connector at the 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 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 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 Engine Control Module.
    • Go to next step: If between 4.8 - 5.2 V 
  4. Ignition ON, verify the scan tool IAT Sensor parameter is colder than -39°C (-38°F).
    • If warmer than -39°C (-38°F). 
    1. Ignition OFF, disconnect the harness connector at the Engine Control Module.
    2. Test for infinite resistance between the signal circuit terminal 6 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 Engine Control Module.
    • Go to next step: If colder than -39°C (-38°F). 
  5. Ignition OFF, install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 1.
  6. Verify the scan tool IAT Sensor parameter is warmer than 149°C (300°F).
    • If colder than 149°C (300°F). 
    1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the 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
    3. Ignition OFF.
    4. 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 Engine Control Module.
    • Go to next step: If warmer than 149°C (300°F). 
  7. Test or replace the Mass Air Flow/Intake Air Temperature sensor.
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