Skip to content
Tahoe / Yukon Service Manual

DTC P112F

Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P112F Radiator Coolant Temperature Sensor Not Plausible Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Signal P00B3 P00B4 P00B4* P112F
Low Reference — P00B4 * P112F
* Internal control module or component damage may occur if the circuit shorts to B+.

Typical Scan Tool Data Radiator Coolant Temperature Sensor

Circuit Short to Ground Open Short to Voltage
Operating Conditions: Engine = Idling — At normal operating temperature. Parameter Normal Range: −39 to 120°C (−38 to 248°F)
Signal 140°C (284°F) −40°C (−40°F) −40°C (−40°F)
Low Reference — −40°C (−40°F) —

Circuit/System Description For an overview of the component/system, refer to: Cooling System Description and Operation

Circuit Description
Signal The control module input circuit has an internal resistance connected to 5 V.
Low Reference Grounded through the control module.
Component Description
B203 Radiator Coolant Temperature Sensor The sensor is a negative temperature coefficient thermistor. As the temperature of the air, fluid, or metal increases, the resistance of the sensor decreases, varying the voltage on the signal circuit.
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.

Conditions for Running the DTC DTCs related to the following system/component = Not Set – B9 Ambient Air Temperature Sensor – B14A Transmission Output Shaft Speed Sensor – B34 Engine Coolant Temperature Sensor – B66 Intake Air Temperature Sensor – B115 Vehicle Speed Sensor – B203 Radiator Coolant Temperature Sensor Ambient Air Temperature = Warmer than −20°C (−4°F) Engine = Off — For greater than 6 h Engine = Running Engine Block Heater = Inactive /Not Detected Fuel level = Greater than 10% Frequency the DTC runs = Once — After the running conditions are met Conditions for Setting the DTC Radiator Coolant Temperature Sensor / Engine Coolant Temperature Sensor / Intake Air Temperature Sensor = Not within a calibrated range Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B DTC Diagnostic Aids After starting a cold engine, the following scan tool parameter value should rise steadily and then stabilize: Radiator Coolant Temperature Sensor Reference Information Schematic Reference Engine Heating/Cooling Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Verify the coolant is at the correct level. ⇒ If not correct Repair as necessary » Refer to: Loss of Coolant ⇓ If correct
  2. Ignition/Vehicle » Off — For greater than 6 h
  3. Ignition » On / Vehicle » In Service Mode
  4. Verify the scan tool parameter: Engine Coolant Temperature Sensor / Intake Air Temperature Sensor / Radiator Coolant Temperature Sensor = Within 9°C (16°F) of each other ⇒ If not within 9°C (16°F) of each other { Engine Coolant Temperature Sensor } Refer to: DTC P0117-P0119, P2184-P2186, P2B2D, P2B2E, or P2BB5 { Intake Air Temperature Sensor } Refer to: DTC P0097-P0099, P00F4-P00F6, or P0112- P0114 { Radiator Coolant Temperature Sensor } Refer to: Circuit/System Testing ⇓ If within 9°C (16°F) of each other
  5. Verify the scan tool parameter: Radiator Coolant Temperature Sensor = −39 to 120°C (−38 to 248°F) ⇒ If not between −39 and 120°C (−38 and 248°F) Refer to: Circuit/System Testing ⇓ If between −39 and 120°C (−38 and 248°F)
  6. Verify the scan tool parameter: Radiator Coolant Temperature Sensor = The value should not spike or drop out. Perform the action while monitoring the parameter: Wiggle the harness and connector: B203 Radiator Coolant Temperature Sensor Wiggle the harness and connector: K20 Engine Control Module ⇒ If the value spikes or drops out Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If the value does not spike or drop out
  7. 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. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC is not set
  8. All OK. Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector: B203 Radiator Coolant Temperature Sensor
  3. Test for less than 10 Ω between the test points: Low Reference circuit terminal 2 & Ground ⇒ If 10 Ω or greater 3.1. Disconnect the appropriate electrical connector: K20 Engine Control Module 3.2. Test for less than 2 Ω between the test points: Low Reference circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇓ If less than 10 Ω
  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 5.1. Ignition/Vehicle » Off 5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 5.3. 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 ⇓ 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 7.1. Ignition/Vehicle » Off & Remove » Jumper wire(s) 7.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 7.3. Ignition » On / Vehicle » In Service Mode 7.4. 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. ⇓ If less than 1 V 7.5. Ignition/Vehicle » Off 7.6. Test for less than 2 Ω between the test points: Signal circuit terminal 1 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇓ If warmer than 139°C (282°F)
  8. Test or replace the component: B203 Radiator Coolant Temperature Sensor Component Testing
  9. Ignition/Vehicle » Off
  10. Disconnect the electrical connector: B203 Radiator Coolant Temperature Sensor
  11. Verify the value is within the range listed in the table: Temperature Versus Resistance ⇒ If not in the specified range Replace the component: B203 Radiator Coolant Temperature Sensor ⇓ If in the specified range
  12. Test for infinite resistance between the test points: Each terminal of the component & The component’s housing ⇒ If less than infinite resistance Replace the component: B203 Radiator Coolant Temperature Sensor ⇓ If infinite resistance
  13. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Engine Coolant Temperature Sensor Replacement - Radiator — B203 Radiator Coolant Temperature Sensor For control module replacement, programming, and setup refer to: Control Module References