Mystery Master Warning light. No check engine light. No codes.

Discussion in 'Generation 1 Prius Discussion' started by lmarcucci, Jun 16, 2014.

  1. lmarcucci

    lmarcucci Junior Member

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    Hi everyone,

    I bought a 2001 prius with 140k on it with a bad MG2. Long story short. I replaced the transmission with a low mileage tranny from the junk yard. The car drives fine now. However, when i click the key to on, the ready light doesn't come on. The Triangle of death comes on and on the MFD, the icon with the exclamation over the car is red. The weird thing is, there is no check engine light. Now, if i try to start the car, it will start if i give it a few tries. And the car drives fine. I drove it around the block and there were no stuttering or juddering issues anymore.

    I have an elm327 and Torque. I scanned for codes and there were no codes. I sent the clear fault codes command and the light came right back on in a matter of a second.

    I also checked the 12V battery because i've had priuses in the past that have bad 12v's and they cause all sorts of issues. My 12V is a new battery from the dealership(previous owner had it installed). and it shows 12.7v when i hook a multimeter to it. I tried disconnecting the battery and reconnecting it a few times. No go.


    Does anyone have any idea what it could be? Would low transmission oil cause a prius to detect a problem without even starting the car? I checked the coolant level and it's find. Inverter coolant is barely above the low line. Should I fill it up some more? Again, the prius detects this issue without even starting it. Disconnecting the 12v and reconnecting, it still even detects the problem without starting the car, just having the key in the on position.


    Thanks for the help!
     
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Since the MFD shows the warning icon of the ! superimposed over the car, DTC definitely exist, logged by the hybrid vehicle ECU and/or the traction battery ECU. I suggest that you obtain Mini VCI so that you can retrieve the fault codes.
     
  3. bwilson4web

    bwilson4web BMW i3 and Model 3

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    The symptoms are consistent with the inverter interlock signal that comes from the inverter, through the micro-switch on the orange traction battery, back to the HV ECU. A rather obscure signal, the symptoms can be replicated in a working Prius by half-unlocking the orange safety lock.

    Cycling the orange traction battery interlock may clear the problem. However, it is more likely the signal got blocked when the inverter was moved from the old transaxle to the new one.

    I think we wrote something up about this several years ago. It would be a Prius unique code, if I remember correctly. I tried to measure the signal but had no luck figuring it out.

    GOOD LUCK!
    Bob Wilson
     
    #3 bwilson4web, Jun 16, 2014
    Last edited: Jun 16, 2014
  4. lmarcucci

    lmarcucci Junior Member

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    So, If i bought a mvci(already found the techstream 8.30 software as a free download after some long googling), which i should do anyway, will techstream be able to read the inverter interlock signal code?(is it even a code?) I'll disconnect the hybrid battery and disconnect the 12V for a minute or two and see what happens. When I did the swap, All i did was remove the terminals, i never pulled the orange safety interlock on the battery(Yeah, yeah, i know it was not a safe thing to do. I wore protection :))

    Edit: Also, due to the fault of the junkyard, I have the inverter that came with the new transaxle.

    Thanks for your help guys.
     
    #4 lmarcucci, Jun 16, 2014
    Last edited: Jun 16, 2014
  5. lmarcucci

    lmarcucci Junior Member

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    Woops, do you mean you tried to read the signal with a scan tool or a multimeter? (Look at me showing my ignorance!)

    Edit Edit: Wow, I love amazon. Ordered a MVCI with a free trial of amazon prime with one day shipping for $31($27 MVCI + $3.99 one-day shipping)
     
    #5 lmarcucci, Jun 16, 2014
    Last edited: Jun 16, 2014
  6. lmarcucci

    lmarcucci Junior Member

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    [​IMG]




    TAHHHH DOHHHH!!!

    So, if anyone ever has the P3140 problem, check your inverter terminal covers!
    [​IMG]


    The terminal cover that goes over those terminals pictured above(I think those go to MG1(Don't quote me on that)), has a connector on it that goes into that white connector on the lower left hand side of the terminal case. The connector on the cover literally has a jumper in it, and all the white connector does is close a circuit that senses whether or not the cover is over the terminal case securely. If the cover is not on, not on correctly, or if the pins on the white connector pins are bent(like mine pictured in the top photo), you will get a P3140. You will get a triangle with no CEL. The only way to pull the code is to get a mVCI and techstream. The ABS light may flash as well. By the way, this also will happen with the terminal cover in the lower driver side of the inverter. You will get a P3140 and ABS light may flash as well. Just like the terminal shown above. This has been tested on two different priuses. CHECK YOUR TERMINAL COVERS PEOPLE!

    P.S. I haven't removed the actual large silver inverter cover to check if it also has a sensor on it. I will do that tomorrow.
     
    #6 lmarcucci, Jun 18, 2014
    Last edited: Jun 18, 2014
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