UPDATE: Mystery Warning light P3140

Discussion in 'Generation 1 Prius Discussion' started by lmarcucci, Jun 17, 2014.

  1. lmarcucci

    lmarcucci Junior Member

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    Hi everyone,

    I received my Mini VCI and sure enough the code was P3140 off of the hybrid ECU. My little bluetooth OBD2 scanner and torque just wasn't enough.

    I tried removing and reinstalling the orange safety lock on the battery, and I even tried pulling one off of my other running(with no warning lights or CELs) GEN1 prius. It still gave me the warning light.

    The funny thing is that when I tried to clear the code with Techstream, my prius behaved the same way as when i tried to clear it with torque. It kicked it off for a second, then the engine died, and a check engine light came on(the CEL went off when I restarted the car).

    I noticed that the inverter coolant hose routing was basically reversed. Would that cause this? I'm going to fix it tomorrow. I had my auto tech friend do this swap, this time. He attempted to do it without labeling anything besides major things.

    I compared all the other inverter wiring with other perfectly running GEN1 and another working inverter I had laying around and I sat it on the ground in between the cars. There really aren't that many wirings going to it. Nothing that looks like it could have been mis-plugged.


    Do you guys have any ideas? Research said to check the inverter casing, but everything looked untouched.
     
  2. bwilson4web

    bwilson4web i3 and Prime

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    We never figured it out. What pissed me off is I could not characterize the signal on a working Prius. It remains a mystery.

    Bob Wilson
     
  3. lmarcucci

    lmarcucci Junior Member

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    LOL. great. I'm totally F'd then. It has to be something electrical since it detects the error upon putting the key in the accessory position after leaving the 12V battery disconnected(Clearing the codes).

    I was doing more research and people said to check for any pinched or damaged wires around the inverter. And to also check the inverter cover sensor. I have two working inverters(one from my other running gen1 and the other from a working gen1 inverter). Someone also said to check the two pin wire connected to the HV battery near the orange service plug. So, i'll check on that tomorrow and post my results.
     
  4. 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.
     
    Itsmeonprius and bwilson4web like this.
  5. WHCSC

    WHCSC Member

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    I'm getting the P3140 with 350 on my 2003. I've had the terminal cover off twice and all looks good with that connection. I can clear the code but it comes right back when I turn the key. What should be my next step?
     
  6. Itsmeonprius

    Itsmeonprius Member

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    Yeah both covers have that connector. Some sort of safety interlock.

    Posted via the PriusChat mobile app.
     
  7. WHCSC

    WHCSC Member

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    The inverter cover itself has one too?
     
  8. mroberds

    mroberds Member

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    I didn't see one when I took my inverter cover off - the big one that's about a foot (30 cm) on a side, aluminum-colored, and has the "Toyota Hybrid System" sticker on it.

    There is one on both of the smaller covers for the MG1 and MG2 cables. Imarcucci posted a picture of the one that's on the back of the inverter - the one that's about 4 inches (10 cm) on a side and black. The one that's on the driver's side of the inverter - the one that's kind of oval shaped - has one too.

    You can also get P3140 if the microswitch for the service plug isn't closed. This can be because the service plug isn't installed correctly, or you forgot to flip the service plug handle up, or if the tab on the side of the service plug that moves the microswitch lever is bent or broken. (Take a flashlight with you when inspecting this; it's in a dim corner of the trunk.)

    I recently got a P3140 and all was OK with the terminal covers, and the service plug microswitch appeared to be working. However, the contacts in the microswitch had apparently got crudded up after many years of low-current switching service - it would either measure open circuit with the microswitch lever pushed down, or a relatively high resistance value (20 to 40 ohms) with the microswitch lever pushed down, where it should be less than an ohm. I took the microswitch off of the car and tried different things, but what seemed to help the most was blowing in it. :) More info in this post: Chasing info code 123 *without* P3000? Or do I need a better scan tool? | PriusChat

    I hope this helps!
     
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  9. WHCSC

    WHCSC Member

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    Great info! Thanks!
     
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