P0118 with New Sensor, New ECM, and Good Harness, No Voltage

BLUF: New coolant sensor, new ECM, harness resistance and insulation resistance are all good. No voltage at the plug to the coolant sensor on the head.

The lady's Prius had a run-in with a stick at highway speed that went through the radiator. The resulting loss of coolant and overheating blew the head gasket. As I learned from the forums, it was about time for it anyway since it was just over 100k miles.

Thanks to the heroes here on PriusChat, I've replaced the head gasket, water pump, thermostat housing, timing chain, and timing chain tensioner. Due to the amount of coolant that ended up in the oil, I replaced the bottom end bearings and upgraded to the newer style piston head and rings while I was at it. The radiator, AC condenser, fans, and spark plugs were replaced by a shop. I replaced the throttle body after a P0123 code.

P0118 is the last code I have to clear. There's no voltage at the plug to the coolant temperature sensor on the head. The resistance of the harness is less than one ohm. The sensor is new. I checked the resistance of the sensor from D28-64 and 65 and it's 1.4 - 1.5 kohms, right in the band for my ambient temperature and identical to the EGR coolant sensor. I checked the harness to ground per the troubleshooting guide and it's over 50 mohms. There's no voltage at the plug with the car on. I checked the EGR coolant sensor at the same time and it has 5 volts. When I use Car Scanner I get a normal temperature on the EGR coolant sensor and -40F on the head sensor. So I replaced the ECM. I still have the P0118 code and the guide ends there.

Am I missing something?