If I understand how this thing works thers two large post 1 is a line from the battery should read 12 v all the time the other large post is what feeds 12v when the key is on to the glow plugs for up to 120 sec depending on the temp. 2 small post one controlled by the pcm the other by the key with the key off there should only be 12v to the 1 large post. In my truck the 1 large and both small always have power to them, when I turn the key on all 4 posts have power after a 60 sec or so the glow plug lead starts to power down slowly this may take 60 sec to get to 0 v then when I start it .the Glow plug lead goes back to 12v. Is this right should my glow plug lead be powered up with the truck running? I have had this truck for 6 weeks and being my first diesel I dont know much about them.