5r55s issues

Discussion in '2005+ Mustang GT 4.6L Tech' started by Josh McCool, Sep 10, 2019.

  1. Josh McCool

    Josh McCool Junior Member

    i have a 2006 gt with trans issues. its locked in either 3rd or 4th gear with the o/d light flashing. it engages p, r, and n just fine. it will drive forward just fine once its done slipping and gets moving forward fast enough. it has codes saying the shift circuits are not operating. a shop looked at it said mechanically its fine. anyone run into this before?
  2. 08MustangDude

    08MustangDude Resident Fuktard

    It needs rebuilt or replaced, and that's that. Someone can sit here
    and explain the internal workings, but in the end, it's a mechanical
    failure, be it a clutch pack, band or servo...
  3. 07 Boss

    07 Boss Senior Member


    It doesn't necessarily mean he needs a rebuild. It could be something as minor as a pinched wire or bad solenoid. Sounds more electrical to me. Without knowing the codes it could be a bunch of things.

    What were the exact codes given?
  4. 08MustangDude

    08MustangDude Resident Fuktard

    O/D light flashing is an internal failure. I don't know how a SHOP
    can look at it and say, "mechanically" it's fine. They would have
    to take it apart to verify that. Anyone would have to...

    Even if it is a solenoid, replacing the solenoid pack is the solution,
    with an updated one. Solenoids are mechanical, controlled with
    electric impulses. If it is electrical, then the solenoid pack is fine.
    This will also be the easiest fix if a solenoid has mechanically failed,
    and replacing the whole pack is the solution. They're all over eBay,
    and updated versions.

    It is a mechanical failure, you will see... Even if the mechanical failure
    is caused by an electronically controlled device that has failed, it's still
    mechanical. The codes will tell you WHAT is wrong, like P0775, would
    be Pressure Control Solenoid B Malfunction...

    I fit is a WIRE, shorted, or open, then it is electrical. This usually isn't
    the case. Wiring issues causing failures is not a common problem with
    the 5R55, it's almost always mechanical; servos being the #1 issue,
    intermediate, and/or over-drive servo; which applies the bands.

    You post saying you were told it's shift circuits not operating, then you
    do not provide any of the codes. This is why you will get nothing but
    guessing and conjecture. The "SHOP" should have provided you with
    the codes that would be present.

    Most times with these issues with the 5R55, it's rebuild or replace time.
    Consider yourself lucky if all it is, is a solenoid pack, or a wire.
  5. 07 Boss

    07 Boss Senior Member

    Yeah, these things are notoriously weak. I'm on my third, 2nd "built" one. My point was until we get some codes it could be something as simple as replacing a solenoid pack. Clutches and valve body might be just fine, well as fine as can be, all the gears may work and the tranny is just not getting the signal to shift. You ought to think about rebuilding it anyways especially if you are running anything above stockish power levels. This tranny needs many upgrades from stock to make it perform decently like kolene steel clutches (alto reds or like), to servo bores, from input shaft to valve body.

    Anyways, were not going to be able to help diagnose the issue without codes.
  6. 08MustangDude

    08MustangDude Resident Fuktard

    Another thing people do not know, is the two bands are adjustable,
    the intermediate and over-drive band.

    You do want to adjust them so that there is no slip when the bands
    are applied. As the clutch material on the bands wear down , the
    gap widens between it and the drum. The slip, which is a flared
    shift into 3rd or O/D, burns the clutch material. Keeping them adjusted
    keeps the application time and grab strength the same.

    Just some more information the weakness of the transmission... Ford still
    using bands when just about everyone else went to brakes inside the drums.
  7. 07 Boss

    07 Boss Senior Member


    That right there is good to know.
  8. Derf08

    Derf08 Junior Member

    The solenoids are a weak link in these transmission.

    The transmissions themselves are typically fine mechanically with the exception of the input shafts, the intermediate/overdrives servos, and the band adjustments. The rotational pieces rarely fail unless it's a cheap rebuild/reman job.

    Quick test, if you manually adjust the shifter from 1, 2, 3, to D does the car shift fine when driving. If so, it's the solenoid pack or the wiring harness to it that has failed. The "shift circuits" error is a clue.

    Reverse uses a mechanical solenoid although it can fail too, it's not as usual and does not affect forward gears.

    Exact codes would be more helpful but the above test will help you figure out if its mechanical or electrical.