Block Heater?
There are two ways to trace out the entire wire run.
First, the plug should be behinf the front bumper on the driver side, and can typically be found if you reach into the open area behind the bumper through the opening where the fog lights would be (or where they are, if you have them). It is a black cord that is probably zip tied to itself to control potential "dangling wire" issues, and it has a 110V male plug end that has a black plastic cap over it.
Here's another way to find it... Crawl under the truck and look right behind and a little higher up from where your OEM oil filter is mounted. You will see an orange cord coming out of the block. That's IT. The wire can then be traced to the opposite end I first described, and somewhere in that wire run the wire changes from orange to black.
The element sometimes goes bad, and replacements can often be found cheaply on eBAY... sometimes both the cord and the element can be found being sold together.
Hope this helps.







orange cord right next to the oil filter