Unlike our RAV4...this truck has a block heater. Tried it out for the first time yesterday but even though I had it plugged in for a couple of hours, it made no difference when I went to start the truck; the engine guage still showed COLD and it took the usual amount of time for it to come up to temp.
Which makes me wonder...did I have it plugged in long enough (it was about -12C at the time)...or is there another switch or something I need to turn ON in order to activate the heater?

 

Block heaters take around 4 hours to bring everything up the little degree bump it does. The block heater does exactly what it says it heat up the “block buy warming up the coolant. I pulled in the block heater on my 7.3 diesel for years. It for sure helped. However it’s not made for you to get into a warm truck it’s made to help the engine get that cold oil and stuff turning and engine lubricated faster with the slight bump in heat. I hope I made sense there. My 6.2 didn’t come with a block heater but I am thinking about adding one.

 

Mine has a block heater, also, and I plugged mine in, for the whole night, when it was getting close to zero, and noticed no difference either. There shouldn't be any switch in a 12 volt system that controls a 110 volt appliance, so I'd bet, like mine, your's probably just doesn't work like we would expect. But, I'd leave it plugged in overnight to see if that's the case.

 

Your block heater should bring the coolant temp up a bit and you should see the coolant temp gauge indicate so.
Easy check for the block heater...
Check at the cord for shorts and resistance....
1. Hot and Neutral should read about 8-10 ohms maybe a bit more depending on the size of the element.
2. Hot to Ground and then Neutral to Ground should be full open or infinity.
3. If above 1 & 2 do not read correctly unplug the heater side of the plug if able and check the cord for continuity and shorts.. If cord checks good likely the coil.
4. Check the coil at the plug if removable cord it should read like step 1, 8-10 ohms... If not replace coil.

Or just change the entire assembly.

 

Thanks. I will do that.

 

This just reminded me to check the block heater in my 6.2. Had the recall done and they replaced the cord a while back. Don't think I used it since then.

 

My previous truck (1999 F250 with 7.3 PSD) came with a 900 watt block heater. Within 30-45 minutes of plugging it in you could tell the truck warmed up much faster from a cold start. Current truck is 2015 F350 with 6.2 gas engine. This truck came with 400 watt block heater, and even if plugged in all night, there’s no sign of quicker warm up in terms of cabin heat, though the block heater is warm.

 

IME on a 7.3, 5.9 CTD and 6.6 LMM you can hear 'em "hissing" if you listen closely