Replaced fuse box housing - transmission "P" lock mechanism appears

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by TechBill, Apr 5, 2026.

  1. TechBill

    TechBill New Member

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    Update

    Removed broken pin and soldered a new pin from junkyard fusebox. Without putting it back in housing, I reconnected all components.

    Park - No red triangle or P Lock on screen
    Reverse - No red triangle or P Lock
    Drive - Red Triangle and P Lock shows up

    But car still moves in reverse and drive

    Must be one more broken connector somewhere.

    Anyone happened to know which pin lol

    One thing I noticed. very rich gas fume when engine is running.
     
  2. pasadena_commut

    pasadena_commut Senior Member

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    Is it also super loud? A missing catalytic converter has both of those symptoms.
     
  3. TechBill

    TechBill New Member

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    Interesting but no. I been driving it and it went off after i replaced fusebox housing. So far I fixed the two broken wires. Still same result. but got code pulled this time.
     
  4. TechBill

    TechBill New Member

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    After fixing two wires in fusebox .. I ran another scan with techstream. It showed up more devices ..


    IMG_1822.jpeg
     
  5. TechBill

    TechBill New Member

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    One thing I noticed different

    I could get in car and hold brake and press start then it ready to drive before I tried replacing fusebox housing

    Now when I hold brake and press start row of yellows dash light comes on but car not in Ready mode .. I waited a minute still not in ready mode

    If I press start second time .. Ready light come on and car will drive but still red triangle and P lock only in drive. not in Park or Reverse.

    Any idea what could cause this condition?

    Going to clear code now and scan again to see what happens.
     
  6. Brian1954

    Brian1954 Senior Member

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    Do the Techstream health check when the car is in READY, in drive, and the warning lights are turned on.
     
  7. TechBill

    TechBill New Member

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    Does wiper or headlight unplugged causes Red Triangle P Lock in Drive mode?

    I put the car back together (had headlight, bumper, and wiper removed) and now no more Red Triangle or P Lock. I drove around for a bit in town getting about 41mpg and it runs fine so far.

    Bill
     
  8. TechBill

    TechBill New Member

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    I was going to do that after putting car back together but no more Red Triangle or P Lock. Check my previous post. If it comes back I am going plug the Techstream right away but so far drive fine now.
     
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  9. dolj

    dolj Senior Member

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    Neither of those should cause the MWL (Master Warning Light, aka Red Triangle) to come on nor the MFD to display the P-Lock warning.
     
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  10. pasadena_commut

    pasadena_commut Senior Member

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    Sadly that sounds like a loose connection sort of issue. Said connection was bumped/jostled during reassembly and is now temporarily making good contact. Or it might have been a wire shorted to a piece of metal that, similarly, was moved and is no longer shorted. Unfortunately since it is now in the working state you have no way to look for this problem until it randomly shows up again. When you have time to deal with it maybe drive over a bumpy road and see if it shakes loose again..