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Home >> Buick >> 2019 >> Encore Base >> Repair and Diagnosis >> Engine Mechanical >> Cooling System (Mechanical) >> Engine Cooling System >> Diagnostic Information and Procedures >> DTC P112F >> Circuit/System Testing

Circuit/System Testing

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector:B203 Radiator Coolant Temperature Sensor
  3. Test for less than 10 ohms between the test points:Low Reference circuit terminal 2 & Ground
    • If 10 ohms or greater 
    1. Disconnect the appropriate electrical connector:K20 Engine Control Module
    2. Test for less than 2 ohms between the test points:Low Reference circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:K20 Engine Control Module
    • Go to next step: If less than 10 ohms 
  4. Ignition - On / Vehicle - In Service Mode
  5. Verify the scan tool parameter:Radiator Coolant Temperature Sensor = Colder than -39°C (-38°F)
    • If -39°C (-38°F) or warmer 
    1. Ignition/Vehicle - Off
    2. Disconnect the appropriate electrical connector:K20 Engine Control Module
    3. Test for infinite resistance between the test points:Signal circuit terminal 1 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component:K20 Engine Control Module
    • Go to next step: If colder than -39°C (-38°F) 
  6. Connect a 3 A fused jumper wire between the test points:Signal circuit terminal 1 & Low Reference circuit terminal 2
  7. Verify the scan tool parameter:ECT Sensor = Warmer than 139°C (282°F)
    • If 139°C (282°F) or colder 
    1. Ignition/Vehicle - Off & Remove - Jumper wire (s)
    2. Disconnect the appropriate electrical connector:K20 Engine Control Module
    3. Ignition - On / Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:Signal circuit terminal 1 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points:Signal circuit terminal 1 @ Component harness & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component:K20 Engine Control Module
    • Go to next step: If warmer than 139°C (282°F) 
  8. Test or replace the component:B203 Radiator Coolant Temperature Sensor
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