97 Cavalier ECM

Messages
460
Location
Southeast
So guys my gf's 97 cavalier has had a coolant temp sensor issue for awhile that I am now getting around to having time to work with. Long story short, the coolant temp gauge shows no temperature, there's a cel for high voltage to the Coolant temp sensor. I have replaced the sensor with three different brand new sensors, cleared the code, same deal no temp showing on the gauge and the code comes right back. So I replaced the pig tail on the sensor, and metered the voltage coming to the pig tail and it was all within spec. Haynes (It may be another brand will have to ask her grandfather though) manual, plus googling shows this to be an issue that requires replacing the ECM. Now I have found ECM's at Autozone for less than $100. My question is, think this may fix this as well as are there any known issues with new ECM's for this car? I know this has to be preprogrammed and Autozone said that they will need the vin so the manufacturer can reprogram this. So what do you guys think?
 
Messages
2,878
Location
DELAWARE
Rebuilt ECM's are a pig in a poke. Before I would even think of the ECM, I would get a year specific factory diagram and ring out the whole cooling circuit to the ECU. Shotgunning parts is easy but expensive to only find out it was a wiring issue. Also, I think the ECU for your Cavalier is located just forward of the R/H front wheel in the bumper/front valance area. This was not exactly the best area by design for a ECU as road debris and water intrusion were common. If yours is located here, I would disconnect the electrical connections and check for corrosion and/or water intrusion. Good luck!
 
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