Circuit Description
WARNING: This page is about a different car, the 2015 Chevrolet Trax and 2015 Buick Encore. However, it is still accessible from the selected car via links, so may be relevant.
The B203 engine coolant radiator temperature sensor (RCT) 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 sensor 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:
| RCT | RCT Resistance | RCT Signal Voltage |
|---|---|---|
| Cold | High | High |
| Warm | Low | Low |