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I just became the new owner of a new project: a '76 F150 4WD 4spd, with a 400 that must've been swapped in at some point in the truck's life (I believe they didn't come with 400s until later years?)!
I started diving into it by trying to track down a parasitic battery drain, and in the process realized that the engine wiring does not match up well at all with the generic diagram in the back of Chilton's manual for the '74-'78 F-series trucks (which I think makes sense if the 400 was swapped in...).
To make matters worse, it's not a great (re)wiring job (looks pretty hacked up), and the mess continues into the cab, where the fuse panel doesn't match up with what Chilton's says, connections are missing on one end, etc.. I've thought it could be that the cab wiring, while mangled, might be stock (or more stock than the engine) and Chiltons' has some inaccuracy due to trying to cover a whole bunch of years' worth of trucks, but the short of it is: I'm wondering if it is worth investing in a wiring harness from LMC, etc., or if I should do my best to fix the bad parts of the existing engine and cab harness.
I am cheap, so I try to fix things myself. I know on the later trucks (1980-up) they don't have harness kits. Be careful, they do try to sell harness kits but if you read the fine print you find out they are "universal" and give you a new fuse box and marked wires, and that is it. No OEM plugs on the wires to plug into the all the switches and components. If I have to splice and solder all the old ends onto a $500 dollar wiring harness, I might as well fix the original harness myself.
If you want a possibly better wiring diagram, look here.
On your plug in harness for the rear there is two sets of wires purple and orange and the other one is orange and gray they need to loop back into the plug everything works fine now if your truck came with a box and wasn't a cab chassis they will have these wires for blind spot Assistance. Sober both orange and gray ones back into each other and same with the purple and orange ones
07-19-2017, 05:55 PM
