Rip-n-tear time

  Modifications would certainly involve taking apart various covers and trim to access the wiring needed, so investigation of that proceeded during the first big bottom-to-top charge.  As long as the wiring itself remained connected while charging was going on, there was still no harm in displacing a little plastic, and then the serious track-down of electrical stuff could happen later.  Besides, just going into this I didn't have the necessary documentation yet.

For those thinking "but geez, you're gonna totally void your warranty a week into ownership!" ... two words: Magnuson-Moss.  Google it.

Battery service plug access under rear seat The rear seat cushion came out fairly easily, allowing a look at where the service plug for the main pack is.  Getting any farther than this was a fail for now; the cover to access it through the floor of the car is *glued* in place and I didn't feel like uprooting that at the time.  I suppose the expectation is that there will rarely be occasion to internally disable the pack, unless something crazy happens like welded main relays or a bad BMS module and the whole pack has to be dropped for service.  Same principle as any other high-voltage pack, though -- the service plug breaks the string roughly in the middle, and allows access to the main battery fuse which in this case is 600 amps.

Rear under-cover removed, path to lamp sockets I knew I would want to change out some lamps, the reverse-light bulbs at a minimum, so access to them was needed.  After pulling apart some of the interior trim in the rear, I found that not only is there no convenient access behind the lamp assemblies like in the Prius, there is a wall of *body metal* between there and where the lamps actually are!  So that path is a fail [red].  It turns out that the lamp sockets insert from below [green], accessible once the rear under-cover plastic is removed.  So yes -- to change directional or reverse bulbs, you lay on the ground under the butt of the car and and fish your arm straight upward into the hollow bumper assembly.

There's actually a *lot* of wasted air space around the rear of this car in general, but again, it's not getting stripped to the walls to be a freight-hauler.

Dash ripped apart As I began adventuring around the dash I did not know at first which of the many connector blocks I'd need to tap in near to add my mods.  It was still useful to pull interior trim and see where they all were, because then I could start relating their locations to the service information.  To obtain that I signed up for a Techinfo subscription and began pulling down schematics and connector lists so I'd actually know what I was looking at here.
For making mods of any sort, there are three critical aspects of knowledge needed about any given car.  The overall schematic, to see how a subsystem is designed and wired in; the connector diagrams with pin numbers and wire colors and hopefully descriptions of each pin along with; and then the *location* of each relevant connector.  Once I got onto Techinfo I pretty much knew what to look for, and while it was a bit more tedious than "wget"ting a bunch of PDFs like back in the Prius days and thus less complete, I downloaded a bunch of helpful stuff.  Interestingly, Hyundai's service info calls part and connector locations out on *photographs* of partially disassembled cars, rather than the line drawings used in the Prius docs.  Not sure which is more clear, really.

Once the "big recharge" was done I could freely work on the wiring itself, and the next few days held quite a bit of exploring.

Daytime running lights disabled, lugs out of connector It didn't take long to learn what powers the daytime running lights and what connector their wires come out of.  I broke out my set of tiny connector-lug tools and simply backed the two relevant sockets out of the block and taped them back out of the way.

The bigger connectors here have built-in self-ejector levers, which helps avoid having to pull on any wiring.

The large beige structure is called the "integrated gateway and power module", and is Hyundai's variant of what the automotive industry calls a "smart junction block" or SJB these days.  In effect, the Prius body ECU is also one of these, embedding control electronics, relays, power distribution, and fuseholders all into one honkin' module.

Overall CAN network diagram In the Kona it's gotten even more complex, with the "gateway" function also serving to route between at least four CANbus networks.  This is the overall network diagram for the Kona, kindly provided by a somewhat mysterious researcher called JejuSoul, who I'm guessing is Korean and has contributed a lot of interesting OBD-2 and data-extraction information for several Hyundai/Kia vehicles to the community.  [That is more deeply explored in the "data" section.]  Not only does the gateway relay to the four major operational networks, many ECUs are also dual-homed onto more than one network themselves.  Cars bear a striking resemblance to commercial data centers these days, and it's likely that the gateway also has functionality to firewall off some networks and modules from each other and only pass certain types of needed packets.
Another technical take on this and a module glossary can be found on a possibly-unofficial service info site called "hkona", although that's geared toward the gas Kona rather than the EV.  The body electrics across both models are pretty similar.

Note carefully that the car's J1962 diagnostic connector brings nothing but a tiny stub network out from the gateway.  It physically runs all of about six inches to the IGPM, in fact.  Not only does every diagnostic query to any ECU in the car have to get brokered by the gateway module, it's impossible to just plug into that and passively "listen to the bus" like in the Prius that has only one network.  Serious CAN debugging/reverse-engineering would need deeper digging around and modding in direct taps into some of the other networks instead.  The folks over at EVTV Motor Verks had to do this to even get started on many Teslas, which don't have any standard diagnostic connector at all.

Left-dash button board The little switch-panel at the left side of the dash is a single board, with membrane buttons that the external switches push.  I could not see a provision for the VESS-disable switch or other features the car didn't have, so evidently the boards and button arrays are one-to-one matched.  There's still VESS wiring in the connector leading to this, however.  Not really important, as the speaker was simply pulled anyway.

The curvy yellow wire in the background is one of my test clipleads; it didn't take long to get comfortably back into that "wires hanging out of the dash" state.  As networked as these cars are now, the process of analysis and modification in the *analog* domain hasn't changed much.

Prototyping yuppie button diode-spider idea Specifically, the clip was part of a quick and totally redneck test of Yuppie Button basics, with two diodes hanging in space feeding a couple of brake-light lines as proof of concept.  The Button is fully described in its own section, but it's worth noting that almost everything I'd ultimately need to do for it would happen right here at the main junction/fuse block rather than down at the front-to-back harness connectors behind the kick panel.  At this point the physical button was in and nominally usable on a test basis, and as sketchy as that lashup was, it was a nice exhibit to show geeky folks at a social gathering that weekend.  "Yes, I've only had the car for a few days"...

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