Hello all. I have 95 z28 with 82k miles on it I just bought a few months ago. I've been getting a code 15 high voltage open circuit code in the temperature sensor from my code reader. I have replaced my temperature sensor twice making no difference. The computer is reading -40 for a temp.

I did a test with a voltmeter and have the 5 volt in the power. The problem is my ground (black wire) is reading around 180 ohms and a small amount of voltage in the ground 6 millivolts or so. I traced it all the way back to pcm and there is still almost 50 ohms and small voltage at the pcm. Do I need to replace the pcm? Thanks in advance

 

The ground comes from a circuit in the PCM. It is not at the same potential as the chassis ground. Hence the resistance and voltage you are getting on the ground wire, which I assume is referenced to a chassis ground, seems normal. If you got 5 volts between the two pins in the connector (connector off the sensor) that's all you need. Check the two pins for damage or corrosion that might prevent good contact with the sensor.