I left the house in my truck the other day and driving up the highway the cluster dinged and I looked down and it said "check gauges". So I did and the temp gauge was tacked out. I pulled over, shut the motor off and looked under the hood. There was no steam and it was not overflowing in the reservoir so I drove it home. about halfway there the temp gauge just quit and went to all the way to cold and a check engine light came on as well as the ETC warning lightning bolt deal. Sigh. I lost some fluid on the way home and it was boiling over after I parked.

All that being said, last year I put a new radiator, water pump, and thermostat on. I went ahead and pulled the code and it was p0118. I figured it was the ECT sensor so i went and bought one and went ahead and bought a new thermostat while I was at it. Long story short, I have a new ECT sensor in (the old one was good, I tested it) and I have tested the wiring back to the PCM and every thing checks out. I have 5 volts getting sent to the sensor, the new sensor has resistance, the ground wire has continuity back to the plug at the PCM as does the live wire. I can put the millimeter contacts on the 2 pins that go to the ECT on the plug for the for the PCM and throw ohms on it and have have resistance. I am good from the PCM to the sensor. The plug on the wire harness for the sensor passed all the tests. I still do not have a reading on my temp gauge and the check engine light is still on as is the ETC warning light. I did replace the throttle body and reset the pedal accelerator sensor and the light just came back on. I think the 2 are unrelated but I am not sure.
My question is, where do I go from here? I think the problem is in the PCM or from the PCM to where ever it goes. I have found the plug on the PCM with the same color wires that go in the direction of the temperature gauge and ECM. Sigh. Do I chase that?????
I really need to get this resolved because I don't want to be out in the middle of no where on a hunt with kids and the truck shuts down. I am driving it but not going far. It does not run hot. I think the old thermostat failed and caused the initial over heat. With the new thermostat in it runs fine. I have been checking it periodically with a laser temp sensor. But the temp gauge in the truck does not read and its nerve racking driving it around. Not to mention it wont' run right if it isn't' able to read the temp.
Please advise