Need some help tackling a rear ABS wheel speed wiring harness replacement.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by h1ph0panonymous, Aug 4, 2025 at 8:33 PM.

  1. h1ph0panonymous

    h1ph0panonymous Member

    Joined:
    Oct 9, 2023
    249
    33
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    I have an idea where the rest of the wire leads to through the wheel well (into the trunk in the corners like where battery sits) but the rears don’t have a wheel well cowl on my model and year? It’s plastered with some sort of rubber material and even more where the wiring harness goes through the wheel well. Do I cut through it with something (what exactly do I use to open or cut it open or not?) to get the new wiring harness in to plug it up to the ECU bus in the trunk but most importantly what exactly is that rubber material? (So I can replicate the plaster and patch with that same rubber like weather sealing material)
     
    #1 h1ph0panonymous, Aug 4, 2025 at 8:33 PM
  2. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    12,148
    4,930
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    That sounds about right... Other thing you can do is look at as many images of that part that you can find online and confirm if it always comes with plug attached and not just bare wires and that will confirm that cutting through that material and then sealing it back up is the proper way to do it. Of course you could upgrade by replacing a portion of that material with a grommet.
     
    #2 PriusCamper, Aug 4, 2025 at 10:37 PM
    h1ph0panonymous likes this.
  3. h1ph0panonymous

    h1ph0panonymous Member

    Joined:
    Oct 9, 2023
    249
    33
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    Thank you. I can’t find anything online about the Gen 3 Prius repair for this exact replacement harness so I’m just guessing from here, would you use an exact knife for this if you were doing it, can’t imagine anything else that could be thin and sharp enough to work around the wire and not cut anything else on accident. I did find “universal” splice job videos but comments all say these harnesses are Ohm sensitive by 1 Ohm, I have no clue how much length of wire equals one Ohm. I might try it myself with some solder just will need to buy a solder and make sure it’s for electrical work but also an actual splice harness and not the full harness I already purchased only if find the other end in the trunk is a complete pain in the butt. I’ll update this thread for future users to search this exact repair as no one really here has done it.
     
    #3 h1ph0panonymous, Aug 5, 2025 at 2:57 AM
  4. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    12,363
    2,192
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Use a plastic dowel lightly pointed to push thru the rubber 3M body shutz or it aerosol equals will seal ya back up no worries.
     
    #4 Tombukt2, Aug 5, 2025 at 9:06 AM
    PriusCamper and h1ph0panonymous like this.
  5. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    12,148
    4,930
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    As long as you don't increase or decrease the length of the wires the Ohms should stay the same... Of course the ohm could change dramatically if don't do a good soldering job.
     
    #5 PriusCamper, Aug 5, 2025 at 2:04 PM
  6. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    26,737
    17,524
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    If this is a gen 3 thread, the gen 3 wheel speed sensors make fixed-amplitude, logic-level signals. I'm skeptical of any comments you're finding that say the resistance is all that critical. The normal attention you would pay to not making a bad splice ought to be enough.

    The skid ECU has an extra-sensitive Signal Check Mode you can place it into and drive around for a bit and see if it detects any hints of problems. The repair manual says to use this mode after any replacement of the bearings or speed sensors anyway. If you get through that extra-sensitive check, passing, you can be quite confident of your repair for normal use.
     
    #6 ChapmanF, Aug 5, 2025 at 2:18 PM
    h1ph0panonymous and PriusCamper like this.
  7. h1ph0panonymous

    h1ph0panonymous Member

    Joined:
    Oct 9, 2023
    249
    33
    0
    Location:
    Minnesota
    Vehicle:
    2014 Prius
    Model:
    Four
    It was a universal splice YouTube video for abs harnesses that I read the comments in saying these types of wirings are Ohm sensitive up to one Ohm sensitivity. I might just buy the splice versions they have on rock auto and try that first but I sure as heck would like my regen braking back as soon as possible, my hybrid battery is probably getting weaker and weaker without it (2000 miles since disabled), relying on engine-to-inverter energy too much for a recharge, I’m guessing that can’t be healthy for it or lacking a maintaining of it without that extra recharge it gives from braking. I’ll just research proper splice and solder jobs so I know what type of solder metal I need and the correct technique.
     
    #7 h1ph0panonymous, Aug 5, 2025 at 4:17 PM
(You must log in or sign up to post here.)