Scratch Built Harness - Part 1 (Fabrication)

Written by Tony

Tuesday, 25 November 2008 03:27

If you intend to scratch build your harness, you will need a few things from the garage: A pair of saw horses One (or better two) 4 X 8 sheets of 1/4 or 1/2 inch plywood Some nails about 4 inches long If you have a two car garage you can afford to tie up for a few days. Set your saw horses up next to the vehicle to be wired, and join and place your plywood on top of them. You should now have a platform about the size of the vehicle to be wired. Get a magic marker. Draw a rough outline of the vehicle, side to side, front to tail, with lines for the firewall, dashboard and trunk spaces on your plywood.  Measure and show headlight locations as well as tail lamp locations.  Studying your vehicle. Determine the course of harness routing and areas of location for the fuse buss, battery, dash, engine bay harness, and all locations for electrical plugs and devices. Make a rough drawing and take measurements from point to point. Transpose those over to your plywood. Draw a line to show routing, and at each termination point drive a nail about 1/4 an inch in your wood, and mark it's function (tail lamp, etc.). Place your plug/socket and pins there (for later). Continue until you have all termination points laid out and represented by a nail on the plywood.  Figure out your wire gauge for each circuit, as predicated on the draw and length of the run. Make a list (Example: tail lamps...21 feet...10 amps...14 gauge black). Your best bet is to make the wire longer than you would expect to use. Add a few feet or more than you will actually need. This will help when finding mistakes or having to cut your terminal off and starting over, plus if you measured incorrectly, or have to route around something, you will not need to splice the wires together.  Starting with your smallest gauge, at the buss, tie the wire there, run it down your marked route line (add extra length for anywhere it must rise or fall within the body) to the nail marked "tail lamp" then mark the wire with a wire marker (available at any hardware store) mark the function and number on your notes and continue the "Wrap" along to the next item (like the right lamp etc.) Do not cut until the wire reaches termination. Continue until all color wire of that gauge are laid out. Then Repeat with the next largest gauge wire, until all wire is laid out nail to nail. Be sure to keep your runs straight and tight, and do not cut the nail ends until all wires are in place. Ad 5% "Spares" and mark then as such the length of the harness...(for future expansion or in case you shoot a screw through one and get a bad wire..)  Tie the bundle up neatly with proper tie wraps nose to tail.  Cut all nail ends at an equal distance, referring to your notes, and wire markers, as to function and number add your firewall connectors/sockets, fuse buss and devices.  Lastly, using a DVOM or "Ring Box" Ohm or ring the harness out point to point for accuracy. Correct any errors, and you should be ready to fit it to the vehicle. < Prev   Next >

Last Updated ( Saturday, 29 November 2008 23:26 )