P00B4
DTC P00B3 or P00B4
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 Descriptors
DTC P00B3
- Radiator Coolant Temperature (RCT) Sensor Circuit Low Voltage
DTC P00B4
- Radiator Coolant Temperature (RCT) Sensor Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The radiator coolant temperature (RCT) 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 RCT signal circuit and supplies a ground to the low reference circuit.
The following table illustrates the difference between temperature, resistance, and voltage:
Conditions for Running the DTC
P00B3
* The engine run time is greater than 10 seconds.
* The intake air temperature (IAT) is colder than 70°C (158°F).
* The DTC runs continuously when the above conditions are met.
P00B4
* The engine run time is greater than 60 seconds.
* The intake air temperature (IAT) is warmer than -7°C (19°F).
* The DTC runs continuously when the above conditions are met.
Conditions for Setting the DTC
P00B3
The ECM detects that the RCT sensor is warmer than 149°C (300°F) for greater than 10 seconds.
P00B4
Note: The scan tool only displays to -40°C (-40°F).
The ECM detects that the RCT sensor is colder than -60°C (-76°F) for greater than 10 seconds.
Action Taken When the DTC Sets
DTC P00B3 and P00B4 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTC P00B3 and P00B4 are Type B DTCs.
Diagnostic Aids
* As the thermostat opens, the RCT sensor temperature should rise steadily, then stabilize once the thermostat opens completely.
* Test the RCT sensor at various temperature levels in order to evaluate the possibility of a skewed sensor.
* If the vehicle has sat for greater than 8 hours, the RCT sensor and the ECT sensor values should display within 3°C (5°F).
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
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 RCT 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. All OK.
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the B203 engine coolant temperature sensor harness connector at the sensor. 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 circuit terminal 1 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 RCT 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 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 colder than -39°C (-38°F)
5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 1.
6. Verify the scan tool Radiator Coolant Temperature sensor parameter is warmer than 149°C (300°F).
7. Ignition ON, verify the scan tool Radiator Coolant Temperature Sensor parameter is at -40°C (-40°F).
• If colder than 149°C (300°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)
8. Test or replace the B203 engine coolant temperature sensor.
Component Testing
1. Ignition OFF, disconnect the harness connector at the B203 engine coolant temperature sensor.
2. Test for refer to Temperature Versus Resistance [1][2]Cooling System between the signal circuit terminal 2 and the low reference terminal 1.
• If the temperature versus resistance are not within the specified ranges
Replace the B203 engine coolant temperature sensor.
• If the temperature versus resistance are within the specified ranges
3. Test for infinite resistance between each terminal and the sensor housing.
• If less than infinite resistance
Replace the B203 engine coolant temperature sensor.
• If infinite resistance
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Engine Coolant Temperature Sensor Replacement Service and Repair
* Engine Control Module Replacement Service and Repair for ECM replacement, setup, and programming
Repair Verification
1. Ignition ON, observe the scan tool Radiator Coolant Temperature Sensor parameter. The reading should be between -39 to + 120°C (-38 to +248°F).
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
3. Verify a DTC does not set.
• If any DTC sets
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
• If no DTC sets
4. All OK