I got a 99 regal runs perfectly fine only issues is the car overheats because the fans will not turn on. I unplugged the temp sensor plug and the fans automatically kick on so I know its not relays or the fans. What could it be? Also after I tried jumping a Fan relay connection and caused a spark the Service Engine Soon came on. It was never on before this and the car has no running issues! Hopefully i can get some answers here THANK YOU :)
you should have the car scanned to see what code is set. While you have it scanned for the code look at the coolant temperature sensor. See if it shows the actual temperature of the engine or does it show something like -40F. If your PCM doesn't see the engine getting hot it won't turn on the fans. If the temperature looks good, let the engine run and get hot while you watch the data stream Watch the values for temp and the fan "on" or "fan request" on or off. the fan should come on at 212F. that should turn the two fans on at 1/2 speed. if the temp gets to 221F the relays change and both fans are turned to high. If you get to 230F the whole system is turned on and all three fans go to high. if the fans don't bring the temp down it's time to stop driving and get over to the side of the road where it is safe and let thing cool down.
so go and see what your code is. clear it. and watch you data stream for your cooling system. see what your computer is doing.