Dead Prius: key will lock/unlock, but nothing on Dash.

Discussion in 'Gen 2 Prius Technical Discussion' started by WaitUntilMorning, Sep 11, 2020.

  1. WaitUntilMorning

    WaitUntilMorning New Member

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    Hello.

    I have a 2007 Prius with 380K miles and it died on me one day while driving. I'm just now getting around to looking into WHY so any help you folks can offer would be appreciated.

    Right now the only thing that I know works electrically is the door locks. I can lock and unlock the car with the key but when i put the key in the ignition and press the power button absolutely nothing happens.

    When it died the car was able to coast to a stop so i could get it safely to the side of the road, but since then the front wheels have locked so i had to tow it and let it sit where the tow truck was able to drop it.

    I've dismantled the HV battery (because i heard the cooling fan whir up before it died and there was a high pitched "wheeeeeeeeeeeeeeeeeeee" that came from the back just before it died) and all the cells were exactly the same voltage (and in range with what they were supposed to be).

    I also put in a different HV battery BUT this is one that i had laying around from when another Prius did the same thing to me (472K miles) so it's possible that both batteries have the same failed part, but i don't have a third battery to try to start the car with.

    What I'm trying to figure out is whether the problem is in the electronics of the HV battery or in the inverter or someplace else that i don't know about. As I said above this is the second prius that it's happened to so it's probably not a completely uncommon problem but my experience with these cars' EV aspect is limited to doing HV battery swaps... i've done the regular mechanical stuff, but never needed to touch most of the electrical parts.

    Is there some known part in the HV battery assembly that is known to fail? are there ways to test things? Any insight would be appreciated.
     
  2. WaitUntilMorning

    WaitUntilMorning New Member

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    oh, damn. I just remembered one other thing. The second battery that I had tried in the car came out of a car that had a similar failure BUT with that car i actually remember smelling smoke/burnt electronics under the hood which is why i even bothered trying out its HV battery on the current dead car.
     
  3. dolj

    dolj Senior Member

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    The mechanical key does not need electricity, it works purely mechanically, after all, it the fallback solution for when the battery is flat.

    My best advice for this situation is to put in a 12 V battery that is known to be good and fully charged then read the codes. If no codes pop up straight away, try to start the car and see if any of the dash lights come on. If there are no dash lights, check that the inverter coolant pump is working by putting the car in IG-ON or READY and see if you can see any positive and definite movement of coolant in the inverter reservoir. It should be from front to back.

    It will save a lot of your time, resource, and energy if you use the diagnostic resources available to you rather than just tack wild as guesses.

    If you do get codes, post them here if you need further advice about them.

    PS, for your second car, also check the inverter coolant pump (and the AM2 fuse also). It could have failed also. Smoke and the burnt electrical smell is a definite indicator.
     
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Your initial symptoms are very indicative of an electrical failure of the inverter cooling water pump, which blows the AM2 fuse in the underhood fuse panel. This kills the car. Has nothing to do with the HV battery.
     
  5. WaitUntilMorning

    WaitUntilMorning New Member

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    Sorry about the delay responding here. I have to move and have spent most of the last few days packing and transporting stuff.

    One of the biggest panics that I've had with the move is that darned Prius sitting dead and unmovable in the driveway. You guys both nailed the AM2 fuse. I checked all the big ones in the fuse box, but didn't even think that a tiny fuse on the outer edge would be the source of a complete car shutdown.

    So while i can't confirm that it is definitely the problem until i get the HV battery reassembled and back in the car (i ordered new bus bars and nuts and they'll be here thursday) it makes PERFECT SENSE that the Inverter Cooler Motor has a short and killed the AM2 fuse (there's even a youtube video that shows the pump actually smoking and then blowing the fuse). I had a code that the pump was failing months ago, but it was intermittent so i ignored it (well, i bought the pump, but didn't actually install it. oops).

    In my head it always felt like this was going to be a simple solution (fuse) since the car went from 100% running to deader than a door nail in a blink.

    I also realized after dolj's response that i should have been more specific with my comment about the doors locking/unlocking. I meant that the power locks worked just fine (with the key fob and the switches on the doors themselves) while the 12V battery was installed. with the working 12V battery installed pressing the POWER button did nothing... no orange light. no green light. no IGN mode.. no READY... no speedo... just a black instrument panel / dash / screen...

    I put a replacement fuse in and I'll get the HV battery reassembled and installed thursday and put the (fully charged) 12V battery back and I feel confident I'll have positive news here (and i'll pull whatever codes pop up).

    thanks so much for the responses. it's very much appreciated.
     
  6. dolj

    dolj Senior Member

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    Does that mean you also installed your new inverter coolant pump? If you haven't yet, unplug the electrical connector to it before trying to make the car READY or IG-ON. The photo below shows an easier place to do this rather than right at the pump.

    Prius Gen II Inverter 3 Power Connector.jpg
     
    #6 dolj, Sep 16, 2020
    Last edited: Sep 16, 2020
  7. WaitUntilMorning

    WaitUntilMorning New Member

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    i haven't changed the pump yet (i was going to try and squeeze it in on friday and it's got a small coolant leak from the radiator that i was going to handle at the same time) but that's another great tip as those fuses aren't cheap (the parts shops near my house only have them in a "variety" pack so it's $6USD to get one and then have all the other "sizes" sitting around never to be used).
     
  8. WaitUntilMorning

    WaitUntilMorning New Member

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    Well, that took longer than I had anticipated. Looking for a place to live and packing AND working in the middle of a pandemic is apparently really time oonsuming.

    I did have a couple missteps along the way, too.. I got a little rebuild kit for the bus bars (nuts and the plates) and reassembled the battery that had been in the car when it died and it kept throwing the Red Triangle of Death at me and was giving me lots of errors about the car not being properly in P but the shifter didn't do anything and the car still didn't go into READY or IGN modes... the dash did turn on though after changing the fuse so yay for that.

    I pulled the HV battery out again and reassembled the spare battery that I had on hand (same rebuild kit) but noticed that i had made a really stupid mistake on the first battery and NOT swapped out the plates on the wired side... I somehow missed the fact that the plates were BEHIND the wired bit and tried to put the new ones over the top which obviously didn't fit because the slot for them was already filled... but being stupid i chalked that up to bad fit rather than my own stupidity. When i was putting in the second HV battery i realized that i had a broken wire (orange with a dark stripe) in the harness near the trunk opening (the car had been rear-ended before and the body shop just spliced the broken wires together again and one came loose). I think that was the cause of the Red Triangle of Death because when i looked at the wiring loom connected to the HV battery i definitely saw a wire that looked just like the broken one. Either way... once i connected THAT battery the car turned on again. I hadn't disconnected the connector that was shown above so the car blew the AM2 fuse again after about 30 seconds but it was definitely on and running. when i opened the hood to check the fuse (i found a 6 pack of 15A microfuses for $3USD at another local parts shop so i had spares now). i definitely smelled the electrical burning so a short in the pump was looking to be the culprit.

    It turns out that the part that i already had on hand was the 3 way coolant valve so I ran out to the local parts shop and got the inverter cooler water pump for $120 (after taxes). When i pulled the old one off there was definitely seepage out the bottom (and there was lots of caked on dirt where the hoses connect so i'm assuming it was coolant leaking that caused them to get sticky enough to hold the dirt together). It also smelled burnt so I was pretty confident that you guys had nailed the issue.

    I got it hooked up and topped off the inverter's coolant reservoir (t was officially at the LOW line) and BAM everything started right up and ran for a solid 20 minutes without any issues. I bled the coolant line a bit and i'll do it again before i actually drive it anywhere. I'm calling this issue resolved though. I feel pretty dumb for having scrapped the other prius that probably just had the same problem... but i gutted it before i let it go (airbags, all the electrical (wiring, sensors, batteries), catalytic converter (which was wise because my mother had hers stolen a few weeks later), trim pieces, doors, hood, fenders, rear hatch, bumpers, headlights, mirrors, etc. so i've got spare parts for most possible needs now.

    thank you guys SO MUCH for your help. I really do appreciate it. Now i can get this prius out of my driveway and take my time selling it rather than having to just throw it up on Craigslist for cheap or free to anybody who could tow it out by my move out date (30 SEP).
     
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