Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P00B3: Radiator Coolant Temperature (RCT) Sensor Circuit Low VoltageDTC P00B4: Radiator Coolant Temperature (RCT) Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
RCT Sensor Signal | P00B3 | P00B4 | P00B4* | P00B6 |
Low Reference | -- | P00B4 | P00B4* | P00B6 |
* Internal ECM or sensor damage may occur if the circuit is shorted to B+. | ||||
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: Varies with ambient temperature | |||
RCT Sensor Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F)* |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)* |
* Internal ECM or sensor damage may occur if the circuit is shorted to B+. | |||
Circuit/System Description
The radiator coolant temperature (RCT) sensor, or engine coolant temperature (ECT) sensor 2, 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:
RCT | RCT Resistance | RCT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
P00B3
| • | DTCs P0112 or P0113 are not set. |
| • | The engine run time is greater than 10 seconds. |
| • | The intake air temperature (IAT) is less than 70°C (158°F). |
| • | The DTC runs continuously when either of the above conditions are met. |
P00B4
| • | DTCs P0112 or P0113 are not set. |
| • | 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 either of the above conditions are met. |
Conditions for Setting the DTC
P00B3
The ECM detects that the RCT sensor is greater than 149°C (300°F) for greater than 5 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 5 seconds.
Action Taken When the DTC Sets
| • | DTC P00B3 and P00B4 are Type B DTCs. |
| • | The cooling fans will be commanded ON by the ECM. |
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 overnight, the RCT sensor and the ECT sensor values should display within 3°C (5°F). |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine idling, observe the DTC information with a scan tool. DTCs P00B3 or P00B4 should not set.
- 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.
Note: The intake air temperature must be between -7 to +70°C (19-158°F) for the DTCs to set.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the RCT sensor, or ECT sensor 2.
- Ignition OFF for 1 minute, test for less than 5 Ω between the low reference circuit terminal 2 and ground.
- Ignition ON, verify the scan tool RCT sensor parameter is at -40°C (-40°F).
- Install a 1 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the RCT sensor parameter is at 150°C (302°F).
- If all circuits test normal, test or replace the RCT sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the ECM. |
Note: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
| ⇒ | If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the RCT sensor.
- Test the RCT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance table and verify that the resistance is within 5 percent of the specification.
Note: A thermometer can be used to test the sensor off the vehicle.
| ⇒ | If not within the specified range, replace the RCT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
