I need to rebuild the injector harness on an old vehicle using Y-splices on the wire to reduce cable usage/lengths (V12 engine).

My question now is how to to the Y-splice on the wires.

  • Soldering
    Seems to be discouraged for automotive use, because stranded wire gets stiff and breaks under vibration. Also high temperatures on top of the engine makes solder brittle.

  • Ultrasonic welding
    Seems to be the professional choice - no access to such a machine tough.

  • Crimping
    I´ve seen a lot of bad homemade crimps - i´m not sure if it is doable with non-professional tools. However, this seems the way to go. Still need a way to join 2 wires

    • Butt Connectors
      they don`t seem to be designed for putting in 2 wires on one end.
    • Crimping Tubes (Aluminum) Found them at a rc hobby supply store - but they are not intended for (stranded)wire use at all Crimping Tubes

    • "Scotchlock" Type
      They are intended for automotive use; however i don`t consider this a permanent or even sufficient electrical connection. enter image description here

Which method and tools should i use? Or is there a better way?

  • There was an answer somewhere in here on different types of splices. The military splice is probably what you're looking for. You don't necessarily need to solder the connection and opinions are pretty split among pros on wether to solder or not.
    – Ben
    Commented Sep 7, 2017 at 16:24
  • As an ex- vehicle electrician worked on heavy earth moving equipment and anything lighter, soldering is best... takes more time but more reliable, however, if you want a cheap and quick and unreliable, in the course of time, fix then use crimps etc...
    – Solar Mike
    Commented Sep 7, 2017 at 17:55
  • @SolarMike I agree, I like to solder splices etc... There is an argument though that it creates a hard spot in the wiring that can break from constant vibrations. Same applies to barrel crimps.
    – Ben
    Commented Sep 7, 2017 at 22:40

2 Answers 2


A properly soldered connection should not break due to vibration. NASA uses soldered splices in their wiring harnasses. See: https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/407%20Splices.html


I have repaired many wiring harnesses with soldered joints (made the joints very slim so that the repair looked as per original once taped up - no bulges etc) both in the engine bay and under the dash.

Soldered joints do not have any problems and, done properly, will have a lifetime longer than the vehicle. However, if you let moisture get in there then you will have corrosion issues, but you can get corrosion issues from wet wiring anyway.

I would seriously suggest that you avoid all those "crimp" tzpe connectors shown in the images - they will all let in the moisture...

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