It is a suprise to me that that sensor caused a check engine lamp in 1997. It senses battery ambient temperature and its usually under the battery tray. It could just be a bad temp sensor 90%, or wiring-plug 5%, or even a bad PCM 5%. Or maybe the weather is beyond the preset parameters programmed in the PCM. I've seen the code, but it usually was used only for charging system field management. So remember that you may need the scan tool to turn off the lamp when repaired, but I think you can just disconnect the battery to shut the check engine lamp off in 1997. Goodluck with your ambient battery temperature sensor. I have not had the privledge of seeing that cause any problems until tonight.
August, 28, 2009 AT 4:51 PM
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.