What is this? It is snapped off of the truck I just purchased. I've never owned a diesel before. Is this the glow plug controller because the wiring doesn't looked hacked up at all but I do not have the one in the next pic.
Thanks in advance for any help or suggestions you can provide.
Yes the top pic is the controller for the 6.9 and known to fail. Search for push button mod, to bypass it. As long as it isn't leaking any fluids I would leave it alone. It is screwed into the head and goes into a coolant passage if I remember right.
Top pic is an early 6.9 GP controller. If you don't want to change over to the bottom pic controller, the 6.9 controller you need is still available on ebay with up dated electronics. To update to the new style GPC, you would need a new GP harness and change the GP's to to the ZD9 where you have the ZD1 now. ZD9 has the pin style connection, ZD1 has the spade connection. If you ever replace the GP's, use the Motorcraft/Beru, if you have Autolite or Champion GP's now I would inspect them for swelling or just burned out. Connect a 12V test lite lead to the POS batt terminal, probe each GP with The wire disconnected, lite should lite if good
Pic is probably the circuit you have now, says 84 -86 but actually 83 to 86. 87 was changed to like your bottom pic. The round GPC checks the coolant temp if needs to be turned on.