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HV ECU Dead! Related to EV Mod?

Discussion in 'Gen 2 Prius Accessories & Modifications' started by Muhahahahaz, Oct 4, 2012.

  1. Muhahahahaz

    Muhahahahaz Member

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    Hi Guys,

    I've never had any problems with my Prius until now. Recently I've been having this problem where sometimes the car won't start (but other times it starts just fine). It's at the dealer right now, and they've just informed me it's a problem with the HV ECU, which will need to be replaced.

    Luckily, this is covered under the factory hybrid warranty, so they said they will replace it for free. (However, I'm worried that they might change their tune if they find my mods and decide that I'm somehow at fault.)

    Is there any way this could be related to the EV Mod that I installed a few months ago (from CoastalETech)? I followed all the instructions exactly, using the correct wires, and the mod has always worked as expected.

    I'm not entirely sure, but wasn't it the HV ECU that I hooked this thing up to? I thought this was a tried and tested mod, so I didn't have any worries about adding it. Now I'm not so sure. Solid-state computers with no moving parts just don't up and die like that, after all. There must be some reason the HV ECU died, right?

    Thanks in advance!
    Muhahahahaz
     
    #1 Muhahahahaz, Oct 4, 2012
  2. lopezjm2001

    lopezjm2001 Senior Member

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    That is the risk of any DIY project. The EV switch is added to USA cars as they are built without a EV switch. The EV switch is factory installed to non-USA Priuses so the mod is more than just tried and tested. I remember reading somewhere that a committee of people decided that the American Prius be built without an EV switch.

    So the fact remains that the fault is probably due to the quality of the DIY install. But then it is possible that the EV switch you installed may have had no impact on your HV ECU but it's death may have been due to an unrelated fault.

    It is possible that the fault might be caused by a bad install of the EV switch and the HV ECU may come good if you remove the EV mod.
     
    #2 lopezjm2001, Oct 4, 2012
  3. Daves09prius

    Daves09prius Active Member

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    Wow that really sucks, Sorry I can't help or offer any advice. I can only say that I'm sorry and I hope someone more experienced than I can help you and answer your questions.
     
    #3 Daves09prius, Oct 4, 2012
  4. pjc

    pjc Member

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    Actually, solid state components do up and die just like that. Electronics have a constant failure rate over their lifetime (as opposed to components that "wear out", whose rate increases over time) -- this means that they will just up and die randomly, for no apparent reason. Reliability is something that is tested and designed in by the manufacturer, but it does not mean that there will be no failures in the field, even under nominal operating conditions. Rare, yes. Zero, no.

    Is it possible the EV mod had an effect? Maybe. But I'd say unlikely. If you damaged some of the other connections or the ECU connector I suppose that could cause it to do something funky. Or if you introduced a huge static discharge to the ECU while installing the mod. Being an on-board automotive computer, though, means that it is pretty robust. More likely is you were just one of the unlucky few that had a random failure.

    It is human nature to always look for a "reason" for everything ("I must have done something to cause this to happen"), but sometimes you just draw the short straw out of the haystack.

    If you were successfully using the mod (that is, you were able to enter EV mode) then I doubt that you installed it incorrectly. It's not that complex a mod (electronically). I would also doubt that reversing the mod would fix the problem, although it is worth a try if you are able....

    I'm sure Toyota would rather blame you for the failure given an excuse, but the dealer would probably rather bill Toyota -- they can charge the full markup and they get a happy customer! So you might be okay.
     
    #4 pjc, Oct 5, 2012
  5. Muhahahahaz

    Muhahahahaz Member

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    Thanks for the reply! Yeah, you're probably right. There's a lot I know about computer stuff, but there's always more to learn! I know what you're talking about, but I tend to think of it in terms of: "This stuff is extremely reliable, so I shouldn't have any problems." Lol.

    So I have my Prius back now, and all is well. They didn't say anything else and everything was covered. They listed the "cost" as around $500 (I forget the exact number), so I'm glad for that hybrid warranty!

    Also, my EV Mod is still working, apparently. That makes sense, because they just need to replace the computer. I guess they leave the wires and plugs alone, so my mod is still attached. :)

    Sorry for the false alarm! I just believe in Toyota quality so much that I figured I must have done something wrong, lol. :p
     
    #5 Muhahahahaz, Oct 7, 2012
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