Battery temp sensor is built into the engine computer which sits next to the battery. They give very little trouble, but must agree with other temp sensors on the engine. For example, if the computer sees that the engine has not been started for over six hours, it expects the battery temp sensor and coolant temp sensor to agree.
Your mechanic will connect a hand-held computer to the vehicle to read the diagnostic trouble codes, THEN he will verify it by reading sensor data. All analog sensors that run on 5 volts must put out a signal voltage between.5 and 4.5 volts. Anything outside that range is how the computer knows there's a problem, sets the code, and turns on the Check Engine light. The light turns on in response to any fault code related to a circuit that effects emissions.
Friday, August 28th, 2009 AT 4:51 PM