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 Descriptor
DTC P00B6: Radiator Coolant Temperature (RCT) Sensor PerformanceDiagnostic 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 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
| • | DTCs P00B3, P00B4, P0112, P0113, P0117, P0118, P0502, or P0503 are not set. |
| • | The ignition has been off for greater than 8 hours before vehicle is started. |
| • | The ignition is ON, or the engine is running. |
| • | The intake air temperature (IAT) is greater than -7°C (19°F). |
| • | The fuel level is greater than 10 percent. |
| • | The engine block heater (if equipped) is not detected. |
| • | The DTC runs once per ignition cycle when the above conditions are met. |
Conditions for Setting the DTC
This DTC sets if one of the following conditions occur for less than 1 second:
| • | The ECM detects the RCT sensor and the ECT sensor are greater than a predetermined intake air temperature at engine start-up. |
| • | The ECM detects the RCT sensor is 20°C (68°F) warmer than the ECT sensor at engine start-up and the block heater has not been detected. |
| • | The ECM detects the RCT sensor is 20°C (68°F) warmer than the ECT sensor at engine start-up and the engine has been cranking for greater than 10 seconds without a fuel level sensor DTC. |
Action Taken When the DTC Sets
DTC P00B6 is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P00B6 is a Type B DTC.
Diagnostic Aids
| • | If the vehicle has sat overnight, the RCT sensor and the ECT sensor values should display within 3°C (5°F). |
| • | 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. |
| • | Inspect for the correct operation of the engine cooling system and verify the correct coolant level. |
| • | If the condition is intermittent, allowing the vehicle to sit for greater than 8 hours with the ignition OFF, may help isolate the condition. Compare the scan tool RCT and ECT temperature sensor values at Ignition ON. 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
- Ignition ON, observe the DTC information with a scan tool. DTC P00B3, P00B4, P0117, P0118, P0597, P0598, or P0599 should not be set.
- Verify the coolant in the radiator surge tank is at the correct level and there are no engine coolant leaks. Refer to Cooling System Draining and Filling and Loss of Coolant.
- Engine idling for 15 minutes with the A/C OFF.
- Command the Engine Coolant Thermostat Heater to 100 percent with a scan tool. Increase the engine speed to 3,000 RPM. Observe the scan tool RCT and the ECT sensor parameters. The RCT and the ECT sensor parameters should be within 20°C (68°F).
- 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.
| ⇒ | If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis. |
Note: Depending on ambient temperature, it may take up to 4 minutes for the temperatures to equalize.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the RCT sensor, or ECT sensor 2.
- Ignition OFF, 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 scan tool 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 specified range, 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 the 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 |
