I transferred my Live wire from my 2007 5.4 to my 2011 Eco and was wondering where the temps that are displayed for coolant temp are taken from? The head or the actual coolant? The reason I ask is during normal driving the fluctuations are rapid. Going up a decent hill temps will go from 200 up to 215 but as soon as I top the hill or ease up on the throttle temps fall back to 200 in seconds. The rapid changes is why I suspect I'm actually seeing cylinder head temps. When towing on a cool day I saw temps up to 225 on hills but hovering around 205 while cruising. Pulling the same trailer with my 5.4 temps would read 200 and may go up to 210 on long hills on a hot day and the temp changes were slow to occur. I'm guessing on that engine I was getting actual coolant temp readings. Anybody know if I'm actually seeing CHTs on my Livewire?

 

I would assume the reading is from the coolant temp sensor. I haven't looked for mine but it seems most are mounted near the thermostat.

 

I may send SCT an email and see if they will answer just to find out for sure.

 

They come from the Coolant Temp Sensor.

I'm pretty sure that cylinder head temp is an inferred value as I'm not aware of a sensor.

 

I'm running a Livewire on my '11 Lariat. She has the 6.2 with Max Tow and a 3.73LS. I have my Livewire set on Coolant temp., Intake air temp., and the dial tach.. I tow a 7x14 enclosed V-nose trailer with my '12 Polaris Ranger 800HD in it. I take it out to my place in West Virginia. On flat roads I average 196-7 Dgrs., fluctuates between 193-200 Dgrs. or so. When I get into the mountains, depending on the incline and length, It will fluctuate 188-212 Dgrs.. There are two longer grades that I've seen it fluctuate 172-215 Dgrs.. But that day the ambient temp. started at about 66 and went up to 96 Dgrs.. My normal cruising temps. (not towing) are:
With Amb. temp. 40-50 Dgrs. - 178-9 Dgrs., fluct. 172-182.
with Amb. temp. 60-70 Dgrs. - 185-6 Dgrs., fluct. 181-192.
with Amb. temp. 80-95 Dgrs. - 194-6 Dgrs., fluct. 185-202.
These are from a towing trip. First pic is traveling on a flat road at 60mph. Second pic is into the mountains at 65mph., and third pic is from going up a long grade then going down the other side.

 

I have a 2013 FX4 Screw Eco. 3.55 gears.
I'm in Texas so mostly warm temps.

My SCT Livewire is always bouncing between 200-207.
I have watched for a few years and this is where it always is. When it gets to reading 206-207 I think the thermostat opens and it quickly drops back to 200 and then 5-10 minutes later its back to 207 and then drops to 200.

I have watched my analog truck gauge and whether my SCT is 200 or 207 F the gauge needle in the dash is always just a shade under half. In other words it doesn't fluctuate at all like the digital reading on the SCT does.
Watching the numbers drove me crazy early on as they are real-time and constantly changing but then learned to double check the analog and see its where it should be.
FWIW