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  • Harness Blueprinting and Layout

    I'm curious what methods other are using to plan out their harnesses.

    Things I'm grappling with at the moment are...

    Determining wire distances?

    How much slack to incorporate for connectors and bends?

    Good place to pick-up bulk wire for the harness?( Is there a place that sales assortment or is it better to buy individuals)

    Ecu Placement thinking about maybe the rear seat or glove compartment? (Battery is in the trunk and secured by battery box and studs passing through the frame rail)

    Just looking for some idea and suggestions on some these things above...^
    Still Got a few part left! Shoot me a PM if you have questions!
    http://www.nissanroadracing.com/showthread.php?t=5286

  • #2
    I measured out trunk lengths, then added around 5% to account for bends and whatnot. Ended up being pretty accurate.

    I made a spreadsheet, and had a diagram that showed the routing, with each trunk measured to the next branch. Took a few hours, but made building the harness much easier to do. Basically plan the harness in excel, double check it, then just follow the instructions you just wrote in excel. Much easier than coming up with everything on the fly.


    I mounted my ECU, fuse and relay boxes where the glove box used to mount on a 1/8" sheet of aluminum. Seems to be working well.


    I got my wire from Wirebarn.com. Good quality stuff.
    '18 Chevrolet Volt - Electric fun hatch for DD duty!


    DefSport Koni Sleeve and Spring Perch Buy!!!
    http://www.nissanroadracing.com/showthread.php?t=5902

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    • #3
      Originally posted by Def View Post
      I measured out trunk lengths, then added around 5% to account for bends and whatnot. Ended up being pretty accurate.

      I made a spreadsheet, and had a diagram that showed the routing, with each trunk measured to the next branch. Took a few hours, but made building the harness much easier to do. Basically plan the harness in excel, double check it, then just follow the instructions you just wrote in excel. Much easier than coming up with everything on the fly.


      I mounted my ECU, fuse and relay boxes where the glove box used to mount on a 1/8" sheet of aluminum. Seems to be working well.


      I got my wire from Wirebarn.com. Good quality stuff.
      Pretty similar to rout I was Leaning towards except I was thinking plexi for mounting the ecu and ground/power distro.

      I had been eye balling i've barns gxl wire for a bit so at least I know now that its a safe buy.

      I was using excel map what circuit's and planning to make a ms visio map or sketup layout of the car.

      Since I don't have access to the car so getting accurate measurement of s13 fast back has been an issue...

      Also I've soldered and epoxy shrink tubed most connection I've with electronics without issue...

      Most source seem to suggest crimp heat shrink tubes or heat shrink solder tubes. Is there any conclusive proof this is better than a proper soldiered joint?
      Still Got a few part left! Shoot me a PM if you have questions!
      http://www.nissanroadracing.com/showthread.php?t=5286

      Comment


      • #4
        Quick question for the engineers on here, what is the difference between Gxl , and Txl high temp automotive wire?

        Comment


        • #5
          Originally posted by konjiki7 View Post
          Pretty similar to rout I was Leaning towards except I was thinking plexi for mounting the ecu and ground/power distro.

          I had been eye balling i've barns gxl wire for a bit so at least I know now that its a safe buy.

          I was using excel map what circuit's and planning to make a ms visio map or sketup layout of the car.

          Since I don't have access to the car so getting accurate measurement of s13 fast back has been an issue...

          Also I've soldered and epoxy shrink tubed most connection I've with electronics without issue...

          Most source seem to suggest crimp heat shrink tubes or heat shrink solder tubes. Is there any conclusive proof this is better than a proper soldiered joint?
          Keep your lengths short for engine harness stuff. the longer the runs, the more susceptible to noise the wires are. things like crank sensors and knock sensors are very low level signals so they are easily affected by noise picked up from other wires (like alternator/power wires).

          mount the ECU as close to the firewall as you can to keep cable lengths short.

          don't use plexiglass as it has a tendency to store static electricity. that would be bad for mounting an ECU. use something conductive like aluminum or steel plate to ensure the ECU housing stays grounded and no static buildup from harnesses rubbing against it or anything.

          solder vs. crimp.. age-old question. solder has tendency for cold joints when not done well- go ahead and solder if you're good at it and have access to good tools. If you're a soldering n00b, with a Rat Shack iron, you're better off with a mechanical crimp as it's pretty easy to ensure a good connection by just yanking on it when you're done. the solder + heat shrink + crimp splices are what I'd use if I wasn't able to build the harness on a bench with a proper soldering iron. (i.e. if I'm crimping wires in an engine bay or under the dash where it's hard to lean over and hold a soldering iron..)

          Originally posted by Cbettis87
          Quick question for the engineers on here, what is the difference between Gxl , and Txl high temp automotive wire?
          http://www.wirebarn.com/Wire-Selecti...de-_ep_29.html

          GXL: "General auto wire"
          TXL: "Thin wall auto wire".

          same type of jacket and same temp range, so others they have the same specs other than insulation thickness. Just for grins, I'd go for the thick wall stuff if the wire will be exposed. If it's all going to be in loom, then I would use the thin wall stuff to keep bundle size smaller.
          Last edited by Matt93SE; 12-09-2014, 08:59 AM.
          Originally posted by SoSideways
          I don't care what color they are as long as they are LONG AND HARD.
          '04 G35 Sedan 6MT- The DD
          '96 240SX- The Track Toy

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          • #6
            Definitely go with TXL - it's closer to factory wire. But it seems they actually use even thinner insulation on most their wiring.

            I used 18 Ga throughout most my harness, just to get a variety pack and compromise. The factory stuff ranges from 18-22 Ga for most stuff, then seems to jump to 14/12 for higher current stuff, but that's obviously not very common in a harness.

            18 Ga TXL is a good compromise IMO, but it is a bit larger than needed on some circuits, so you could mix 18/22 if you wanted to.

            I would also not want to drill into plexiglass - what a PITA that'd be. I'd recommend using aluminum personally - easy to fab, not expensive, fairly lightweight.



            As for soldering vs. crimping, my harness has both, and I had one crimp connection fail after some usage (and yes, all joints got triple pull tested). Other than that, it's fine. I've personally never had a solder joint fail, and it's pretty obvious when you cold solder something visually, but I've seen some pretty bad solder joints over the years done by other people... so who knows.

            IMO, go with whatever you're more comfortable with doing well. For crimping I used uninsulated connectors (they're cheap), and put heat shrink over them myself.
            '18 Chevrolet Volt - Electric fun hatch for DD duty!


            DefSport Koni Sleeve and Spring Perch Buy!!!
            http://www.nissanroadracing.com/showthread.php?t=5902

            Comment


            • #7
              Originally posted by Def View Post
              Definitely go with TXL - it's closer to factory wire. But it seems they actually use even thinner insulation on most their wiring.

              I used 18 Ga throughout most my harness, just to get a variety pack and compromise. The factory stuff ranges from 18-22 Ga for most stuff, then seems to jump to 14/12 for higher current stuff, but that's obviously not very common in a harness.

              18 Ga TXL is a good compromise IMO, but it is a bit larger than needed on some circuits, so you could mix 18/22 if you wanted to.

              I would also not want to drill into plexiglass - what a PITA that'd be. I'd recommend using aluminum personally - easy to fab, not expensive, fairly lightweight.



              As for soldering vs. crimping, my harness has both, and I had one crimp connection fail after some usage (and yes, all joints got triple pull tested). Other than that, it's fine. I've personally never had a solder joint fail, and it's pretty obvious when you cold solder something visually, but I've seen some pretty bad solder joints over the years done by other people... so who knows.

              IMO, go with whatever you're more comfortable with doing well. For crimping I used uninsulated connectors (they're cheap), and put heat shrink over them myself.
              Hmmm thoughts on shielded wire?

              Maybe...
              Ignition coils
              Hall effect sensors (1 of 2 came from the factory this way)
              Injectors(its important in efi so thought I'd at least consider it)
              Last edited by konjiki7; 12-11-2014, 02:52 PM.
              Still Got a few part left! Shoot me a PM if you have questions!
              http://www.nissanroadracing.com/showthread.php?t=5286

              Comment


              • #8
                Originally posted by konjiki7 View Post
                Hmmm thoughts on shielded wire?

                Maybe...
                Ignition coils
                Hall effect sensors (1 of 2 came from the factory this way)
                Injectors(its important in efi so thought I'd at least consider it)
                Follow factory harness for shielding.

                Off the top of my head:

                1. MAF
                2. Knock sensor
                3. CAS/crank/cam sensors
                4. VR sensors for wheel speed sensors if you're using those
                '18 Chevrolet Volt - Electric fun hatch for DD duty!


                DefSport Koni Sleeve and Spring Perch Buy!!!
                http://www.nissanroadracing.com/showthread.php?t=5902

                Comment


                • #9
                  For determining lengths, pull off a long piece of wire, use wire labels every foot, route the wire along the path you're going to take, then you'll know how long to cut your sections.


                  Injector wires shielded would be a waste of money and time, all sensors going to the ecu would be worthwhile. Good grounding as well.

                  Comment


                  • #10
                    I keep thinking maybe TPS is shielded from the factory as well, but I'm not sure on that. Lots of 5V sensors are not (noise is such a small percentage of their range generally).

                    But verify that.
                    '18 Chevrolet Volt - Electric fun hatch for DD duty!


                    DefSport Koni Sleeve and Spring Perch Buy!!!
                    http://www.nissanroadracing.com/showthread.php?t=5902

                    Comment


                    • #11
                      With typical wire quantity lengths if just buy enough to do all of the sensors.

                      Comment


                      • #12
                        True, but if there's no real point...

                        BTW, you can buy shielded MS teflon coated wire for pretty cheap on eBay in random lengths (usually 10-25'). I got a couple of those buys for like $15 total and did all the non-factory shielded I needed to do and had some left over. Good quality wire too. Way tougher than factory shielded stuff.

                        So you don't need to necessarily buy 500' of the stuff.
                        '18 Chevrolet Volt - Electric fun hatch for DD duty!


                        DefSport Koni Sleeve and Spring Perch Buy!!!
                        http://www.nissanroadracing.com/showthread.php?t=5902

                        Comment

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