I own a 2001 Ford F150 Supercrew XLT Triton V8, the original engine blew so I had a 2002 engine installed. For 9 days the truck ran but with problems, every time i put it in reverse it blew the fuse, so I have no reverse lights, the A/C and heater dont work, and the cruise control doesn't work either. Also when I press the On button for the cruise control and hold the cruise button down the horn blows. Now nine days later I was cutting grass, finished working got in my truck to go, turned the key and I got nothing. I checked the fuses another fuse was blown, so I changed it with the same 15 amp fuse, then with a 20 amp fuse all were blown as soon as I turned the key. Could anyone tell me what is going on here, is it because of the harness or the 2002 engine in a 2001 truck.

 

Sounds like a harness was damaged during the engine change.
You need to take a good look all around and down the sides to see where this might have occurred.
There are to many different circuit involved.

 

hey man a freind of mine had a similer problem so he took it back to the shop and they found the big plug at the fire wall was smashed when they installed the new motor .btw his truck is a 99 f150 4.6