How to reenable High Voltage for drive and charging, after an accident?

Discussion in 'Model 3' started by Yusef Ague Gonzalez, Dec 10, 2019.

  1. Yusef Ague Gonzalez

    Yusef Ague Gonzalez New Member

    Hello, I've seen a video about hidden screens in Tesla Model 3, particularly the hidden menu that has access to can bus signals. I'm trying to recover a Tesla Model 3 that was involved in a frontal crash, and was stored for some time, so the batteries (main and 12 V) were discharged.
    I'm an electronic engineer, I like EVs, but before invest in parts to repair this car, I need to know if the car is going to work. I put a 12 V battery, since the original had only 2 volts, the computer starts normally, signaling several errors, since the crash was frontal and affected the front bumper and radiator, I bypassed the coolant to test, and now the only error is "airbags needs service" and "autopilot unavailable". But airbags were never deployed. I opened the penthouse, and check the main battery, it had 75 V, so I connected a charger directly and charged it slowly, now it has 386 V and the computer shows "72 %". But it is not possible to charge with a Tesla charger, nor drive, because the magnetic contactors do not work. I opened the PCU, and all fuses are ok, also the other 3 fuses in the penthouse and the pyro fuse.
    My question is: Why the computers does not turn on the magnetic contactors? the high voltage lines are all perfect. The battery has now a usable voltage, and the two halves are exactly balanced (measuring from pyro fuse to + and -). It is possible that the car is disabled, because of the accident? the title is clean, is not a salvaged car. I don't want to go to Tesla service.
    There is a way to enable the car after and accident, in those hidden menus? Tesla supposedly inspects the car and if they consider that the car is secure, they reenable the HV after an accident. The car has not warranty, so I'm decided to do what is necessary, even soldering in the ICE. Any advise? Thank you very much for reading.
  2. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    You're trying to access stuff that only a trained technician should be messing with.

    If you really want to dive into this, I suggest you contact Rich at Rich Rebuilds. Really, if you start messing around with this stuff the odds are you'll irreparably damage something, or make damage that's already there even worse.

    Rich has messed around with this stuff enough that he generally knows what he's doing, often by trial-and-error. Take advantage of his experience!

  3. bwilson4web

    bwilson4web Well-Known Member Subscriber

    Perhaps you might share more details and photos?
    • That the main batteries were at ~75 V suggests it sat a long time before you got it.
    • Which specific Model 3?
    • Where are you relative to sources of parts?
    • Do you have a "My Tesla" account with the vehicle VIN?
    Bob Wilson
  4. Yusef Ague Gonzalez

    Yusef Ague Gonzalez New Member

    Thanks, I'm trying to avoid the trial and error process, of course. I can disassemble and assemble properly what might be neccesary. So far I have not taken any dangerous action, only have connected a variable high voltage charger to the main battery, that had 75.6 V, now it has 386.2 V and maintains the voltage without the charger, the screen now shows 72 %. It has exactly the half voltage measuring from pyro fuse to + and -, 193.1 V. I have no way to know the BMS state. The magnetic contactors never turn on, so the PCS, drive unit, HVAC, and heater never receive the HV. When connect a Tesla charger, it says "starting to charge", then "charging stopped". Of course the PCS has no HV connection with the battery, it cannot charge. I have performed hard reset, nothing changes. I disconnected the frontal HV cables, for testing, nothing changes.
    Thank you bwilson4web for reading, yes, I think it sat a long time before i got it. But I don't understand why the main battery was discharged, because if the magnetic contactors do not turn on, the main battery should not self discharge so much, unless the magnetic contactors were turning on and feeding the DC-DC converter, and after a overdischarge of the main battery they have been disabled in software even when now the battery is almost full charged.
    I don't understand yor question, relative to sources of parts, I'm in Miami, FL. I'm not the owner, I'm trying to fix the car for a friend who buy it without knowing the damage it had, he has the title but we don't have a Tesla account. He said that the title is clean but reports one accident, of course the car has a front crash. The damage includes the front bumper and headlights. The bumper was replaced to sell the car but it does not have the wiring, so the car wiring that connects to the headlights and everything that is in the bumper, is cutted. I isolated the wires, and I can rebuild the wiring if I can buy the missing section with the corresponding accesories. It is also missing the frontal cameras assembly with the GPS that was mounted in the windshield. The owner does not want to invest any money in parts without know if the car can drive. The rest of the car is undamaged.
    When powered on, the displays shows "airbags need service", and "autopilot unavailable". The LTE, maps with real time traffic, BlueTooth, steering, tow mode, brakes, windows, works normally. It recognizes the card. It has no wifi and I don't know how to enable it. The software is an old version I think, and I don't know how to update it, I can't leave the 12 V battery connected for long time because it discharges, the coolant pumps never stop.
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  5. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    If you're determined to do this yourself, I suggest finding an appropriate discussion thread at the Tesla Motors Club dot-com website, or starting your own discussion there. That's the place to discuss subjects requiring detailed, in-depth technical knowledge about Tesla cars and their operations. Participation is far, far higher there than on this forum.

  6. bwilson4web

    bwilson4web Well-Known Member Subscriber

    OK! What a great project!
    • Coolant pump runs all the time - this would explain the battery drain.
    • Look at: - pricey, it provides access to the maintenance information.
    • Let me suggest for technical data:
      • The only people developing OBD-like monitors hang out there. The moderators are very strong organizers who keep threads well organized. I like 'em.
      • I've found very little, original technical information at "Tesla Motors Club" but they sure have a lot of ad hominem critics too eager to attack this poster with a mob mentality.
    Let me suggest:
    1. Connect with the Tesla service center with title and get a Tesla Account setup. Then ask if they have any historical data available. They are not the enemy and the local folks are often pretty sharp.
    2. Connect with local EV/Tesla clubs. You both are not alone.
    3. IMHO, the 'air bag' alarm suggests this needs to be fixed BEFORE trying any other repairs. Sorry, I have no unique information but the Tesla technical site may have a schematic and traces to identify what may be causing the 'air bag' problem.
    If the owner chooses to give up on the car, contact me privately and we might negotiate something.

    Bob Wilson
  7. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Well then, forget about what I said re asking your questions on the Tesla Motors Club forum. Bob is the engineer here; I'm just a wannabe!

  8. Yusef Ague Gonzalez

    Yusef Ague Gonzalez New Member

    Thanks so much for the suggestions, I will keep you informed
    bwilson4web likes this.
  9. hobbit

    hobbit Active Member

    Interesting challenge. I'll echo that you and Rich Benoit should talk.

  10. fotomoto

    fotomoto Active Member

    Teslas are know for vampire drain of the HV battery while sitting (issue is getting better).

    I surmise the car was left on (maybe from the ax or later from someone "messing around" with it) and the HV continued to drain as well as charge the 12v till it discharged below operating limits (with the 12v lasting a day or two longer).

    The HV battery should have a physical safety disconnect. Emergency responders are trained to look for and use it when dealing with accidents.
  11. Yusef Ague Gonzalez

    Yusef Ague Gonzalez New Member

    Now the HV battery is almost fully charged, 99 %, it has 400 V, and is not self discharging. The safety disconnectors of the HV battery are the pyro fuse and the magnetic contactors. The pyro fuse is intact, and the contactors never turn on, so the HV battery cannot be charged by normal means nor can charge the 12 V battery. I don't know how to upgrade the software, I left the 12 V battery connected and a 12 V charger connected to it, so it remains at 14 V aprox. all the time. Waiting to see if the software upgrade appears, but maybe it never happen because the airbag error, or the missing wiring of the font bumper, or the fact that the PCU is not enabled (the magnetic contactors do not turn on).
    I have no idea what is causing the airbag error, I don't see any airbag deployed.
    Somebody knows if there is some impact sensor in the front bumper, that can be causing the airbag error?
    I'm waiting for the owner to get a Tesla account.
  12. bwilson4web

    bwilson4web Well-Known Member Subscriber

    Sounds like a reasonable approach to keeping the batteries in a 'happy place.'
    I've had an 'air bag' error show up when I'd removed the passenger seat of our 2003 Prius. Although suggested, I don't remember a jumper spoof of the air bag controller working.

    You and the owner might look at:

    I would start with a one day subscription to screen capture as much as possible. The maintenance manuals should include schematics and a fault tree.
    You might try a test account but often the 'one hour' access lasts just long enough to give a clue but not the answer. Navigating these online service web sites can be unpleasant.

    Bob Wilson

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