Hello all. I have a 91 Z28(305tpi auto trans) that is throwing a code 15 (Trouble Code 15 indicates that the Coolant Temperature Sensor (CTS) is reporting abnormally low readings). I changed the sensor and i am still getting the same code. i did disconnect the battery and let it sit for a few minutes to make sure it was cleared. no change. am i to assume there is a problem in the wiring harness or is it possible the ecm is bad? i tried the "ecm in field test mode" and it said it was running in closed loop. i just got this car in a trade deal and really dont know too much about it, but its the car i wanted when i graduated high school and just couldnt turn it down. its got over 200k miles and was badly vandalized a year ago and hacked back together with iroc parts, but i still love it! any help will be greatly appreciated! thanks, AJ

 

this may sound over simplistic but does it have a thermostat? is it taking forever to warm up? If the car was torn up then somewere you may have some cut or bad wires running to or from the sensors to the ecm.

 

Ok. I did find a broken wire leading to that sensor and fixed it. Runs much better now.... IF I can get it to start. There's no pattern on the no start condition that I can see. It just starts when it feels like it. When it won't start it is getting spark and I can hear the fuel pump come on. A shot of ether and it fires right up and runs fine. The car does have a hypertech chip, accel cap and rotor and mad coil. Plugs are new as well. Fuel pump and filter is new as well. I'm at a loss and ready to just give up on it.