I have a 2001 Ranger XLT. I was trying to put in an add-a-fuse to power up a new dash cam. I got it all wired up and I placed the add-a-fuse into the windshield wiper spot with the original 30A fuse and the added 15A one for the cam. Thought all was good so I go to turn the key to ignition and it clicks and I lose all power within my truck. The doors won't lock/unlock and the cabin light doesn't switch on with the doors open. If I turn the key to ignition again, there's no click at all and nothing happens.

I then disconnected and reconnected the ground from my battery and that brings power back on in my truck -- cabin light back on, doors can be locked/unlocked again. I put the original 30A fuse back in the wiper location and tried to go start my truck again and it does the same thing -- a single click and then all goes dark.

I'm quite certain it's not the battery as I had it replaced very recently. I was thinking it might be the security/anti-theft system, but I'm using the original key and I tried locking and unlocking the truck before I went in to start it just in case. Any ideas how to fix this?

 

And you removed and cleaned the positive battery cable as well?
And cleaned the Negative as well

It reads like a battery cable issue, poor connection, if CLEANING the terminals and cable ends doesn't work then follow each cable, positive and negative, to where it connects to vehicle and clean that connection as well

 

That was the ticket! I loosened up the positive side and the terminal just cracked at the bolt from corrosion. Took both it and the negative side off, replaced them with new, cleaned the wires up for good measure, put it all back together and the truck started right up. Thanks for the help!