10 minutes should have been enough. Chris suggested shorting the
positive and negative together to drain any capacitance and force the
ECUs to reset but I cannot imagine an ECU lasting 10 minutes on its
input capacitors. Though, I think that the leaf actually has a super
capacitor behind the rear seats so it might take a long time to drain
that off. It might be worth a try to make sure the 12v wiring is
really, truly drained. I did some work with adding a secondary battery
pack and initially made a number of bad mistakes that caused critical
ECU faults. Disconnecting the battery for a few minutes would not
allow me to clear the faults but disconnecting all day and trying it
again the next day would work. I think eventually someone suggested
shorting the battery terminals and doing that does allow for resets
more quickly. Though, if I'm right about the super cap being for the
12V power then you might want to discharge through a power resistor
and not just click the terminals together. It doesn't hurt to use a
resistor in either case. It's better for the car anyway.

Otherwise, it does appear we're looking at a message that is more
continuous. That doesn't mean that it necessarily happens quickly. On
the Tesla Model S there is a series of messages that transmit the VIN
number of the vehicle, presumably for authentication with various
components. These messages are only sent something like every 5
minutes. So, they'll show up as messages that aren't necessarily one
time and done but they've got a very long interval between
transmission. If you have the means to check transmission interval you
might try that. Actually, I have captures from various Leafs on the
powertrain bus and I do have the means to check the interval so I'll
check and see if I can find messages that maybe don't get transmitted
so often. A validation message might only be every second or couple of
seconds. There's no need to spam the bus with serial number validation
every 10ms. Really, I didn't think there was any need to do it more
than once but maybe it really does. This whole business of component
validation is just plain annoying. Are chop shops really that big of a
thing or are the automakers just that DIY hostile?

On Thu, Jan 26, 2017 at 4:33 AM, Tom Parker via EV <[email protected]> wrote:
> On 24/01/17 23:25, Tom Parker via EV wrote:
>
>> On my car, there is only one frame that isn't repeated continuously after
>> startup (0x603 is sent once, with a single byte payload which is 00 in my
>> captures).
>>
>> I'll try disconnecting the 12v battery tomorrow and see if anything
>> different happens at when it's connected, or during the first startup.
>
>
> I removed the 12V battery and there was no activity on the EV CAN bus when
> it was reconnected. There were also no new messages when I turned the car
> on, and other than 0x603, they all streamed continuously. I waited quite a
> long time (10 minutes maybe) before reconnecting the battery.
>
> I guess this means the BMS authentication is in the repeating messages, or
> it is triggered by some other event than disconnecting the 12V battery, or
> you can have the 12V battery disconnected for a very long time without
> breaking the BMS authentication.
>
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