K20 restomod custom wiring harness

Discussion in 'Workshop Forum' started by Rodger, Apr 28, 2016.

  1. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    As part of my overall K20 swap project, I am doing a full shell up restoration of my '81. I acquired a late model Bertone fuse box and most of the wiring harness a few years ago and my plan is to use that for the new wiring harness for my project. Whoever harvested the harness was in a hurry so several of the end connectors are missing, wires frayed where they were yanked through holes, plus the entire harness was cut in half at just rear of the passenger seat belt mount.

    I am going through it now, removing wires that are not needed for my K20, repairing the breaks on the wires I want, and adding new runs as needed. I am using my original '81 harness as a donor for the missing connections and runs as needed.

    I want to incorporate all of the electrical mods that have been proven successful here on the forum, but since I am totally rebuilding the wiring harness, I want to incorporate these mods into the harness instead of doing them as plug in add-ons. I want to have all of the additional fuses in the fuse box tray instead of scattered here and there, as well as most of the additional relays. The newer fuse box has several relays integrated into it, but there is a side relay holder for 6 additional relays. Most of them are for the AC circuits and a couple are for seat belt stuff. I deleted all of the seat belt related stuff and my car does not have the door courtesy lights, so all of that stuff is unnecessary. My aftermarket AC install has its own wiring harness, that I will incorporate into my new one, and it only has one relay in it. That frees up 5 relay spots to use for various mods.

    Here is how I decided to do the brown wire mod. The newer wiring harness did not come with the battery cables and my '81 original positive terminal was really mashed up, so I elected to cut it off and got an after market one. I ran the starter cable as usual, but for all other power, I had a 6 gauge wire made and ran it from the battery to a fuse panel distribution block I found at West Marine. It has 8 fuses for separate circuits that I will use for all of the various mod runs. I will also take two 10 gauge runs from the same post as the 6 gauge to connect them to the main fuse box and the ignition switch. The extra fuse panel will mount to the rear of the main one like in the picture. The original brown wire junction box was fried.
    [​IMG]
    [​IMG]

    I have a set of Bob Brown's headlight relays and I will mount those in the headlight wells. I also am going to do the wiper motor relay mod and I have a set of fog lamps that will use one relay. Are there any other mods that I should do at this time? My AC system calls for two switched 12v power leads. One has a 30 amp fuse for the blower motor and the other has a 20 amp fuse for the compressor solenoid. I know there are issues with running too many amps through the ignition switch, so I was thinking of using the 25 amp power window relay circuit to power one of the AC needs. I do not have power windows but I noticed that the whole power window circuit is supplied by a relay that turns on when the ignition switch is on so I thought that would be a nice use for that.

    If anyone has any suggestions for improvements, additions, or advice on what not to do, please chime in. Thanks!
     
  2. Rod Midkiff

    Rod Midkiff True Classic

    Location:
    Eugene, OR
    If you are doing such major re-work. Think about saving you some grieve. If you can some how give your self more room under the fuse panel. I had my 86 apart and was not sure if I was ever going to get all the wires back in just the right place to re-attach the fuse panel.

    Love seeing the pic's of other people's projects. (kinda kick's Me into thinking I should get back on Mine).

    good looking stuff!!
     
  3. fiatmonkey

    fiatmonkey Tim Hoover

    Location:
    Redwood City, CA
    Rodger,

    I haven't done it myself, but I like the relay switch mod for the ignition to feed the 12+ for all the electrical(s) that run through the switch directly.

    I plan on doing that soon and will report my results.
     
  4. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    I know what you mean about the number of wires stuffed in there. That is part of the reason I am getting rid of all of the unnecessary wires to simplify it as much as possible.
     
  5. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    I figured by using relays for the headlights, fog lights, and wipers, that should greatly reduce the load through the ignition switch. I also want to figure out the best use of the unused power window relay to not have to route power through the ignition switch.
     

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