P112F
DTC P112F
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P112F
- Radiator Coolant Temperature Sensor Not Plausible
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The engine coolant radiator temperature sensor is a variable resistor that measures the temperature of the engine coolant in the radiator. The engine control module (ECM) supplies 5 volts to the engine coolant radiator temperature signal circuit and supplies a ground to the low reference circuit. The purpose of this diagnostic is to determine if the input from the RCT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the engine is OFF. If the required engine OFF time is met at start-up, the ECM will compare the temperature difference between the actual measured RCT and ECT sensors.
The following table illustrates the difference between temperature, resistance, and voltage:
Conditions for Running the DTC
* DTCs P00B3, P00B4, P0112, P0113, P0117, P0118, P0502, P0503, P111E or P2610 are not set.
* The vehicle has been OFF for greater than 8 hours before vehicle ON.
* The engine is running.
* The intake air temperature (IAT) is warmer than -7°C (19°F).
* The fuel level is greater than 10 percent.
* The DTC runs once per ignition cycle when the above conditions are met.
Conditions for Setting the DTC
The ECM determines the absolute difference of temperature between the RCT start up temperature and ECT start up temperature is greater than 20°C (68°F).
Action Taken When the DTC Sets
DTC P112F is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P112F is a Type B DTC.
Diagnostic Aids
* As the thermostat opens, the radiator coolant temperature sensor signal should rise steadily, then stabilize once the thermostat opens completely.
* Inspect for the correct operation of the engine cooling system and verify the correct coolant level.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Sunshade - Left
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the scan tool Radiator Coolant Temperature Sensor parameter is between -39 to + 120°C (-38 to +248°F) and changes with engine run time.
• If not between -39 to + 120°C (-38 to +248°F) or does not change
Refer to Circuit/System Testing.
• If between -39 to + 120°C (-38 to +248°F) and changes
3. 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.
4. Verify the DTC does not set.
• If the DTC sets
Refer to Circuit/System Testing.
• If the DTC does not set
5. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B34B Engine Coolant Temperature Sensor 2. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohms between the low reference terminal 2 and ground.
• If 5 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If less than 5 ohms
3. Ignition ON.
4. Verify the scan tool Radiator Coolant Temperature 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 K20 Engine Control Module.
2. Test for infinite resistance between the signal circuit terminal 1 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 colder than -39°C (-38°F)
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
6. Ignition ON, Verify the scan tool Radiator Coolant Temperature Sensor parameter is warmer than 140°C (284°F).
• If colder than the 140°C (284°F)
1. Ignition OFF, disconnect the harness connector at the K20 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 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 Engine Control Module.
• If warmer than 140°C (284°F)
7. Test or replace the B34B Engine Coolant Temperature Sensor 2.
Component Testing
1. Vehicle OFF, remove the B34B Engine Coolant Temperature Sensor.
Note: A thermometer can be used to the used to test the sensor off the vehicle.
2. Test the engine coolant temperature sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance Electrical Specifications table and verify that the resistance is within 5 percent of the specification.
• If not within the specified range, replace the B34B Engine Coolant Temperature Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Engine Coolant Temperature Sensor Replacement - Radiator Engine Coolant Temperature Sensor Replacement - Radiator
* Engine Control Module Replacement (LCV) Service and RepairEngine Control Module Replacement (LTG) Service and Repair for ECM replacement, setup, and programming