Killswitch: Best Practice for Manually Immobilising a Prius C?

Hi all,
While my intents are modification, I’d like to discuss the technical side of this issue before I break out the angle grinder and soldering iron.

I’ve been trying to think of the best way to safely disable my Aqua, and would like to discuss the possible options.
We’re assuming, for sake of argument, that someone has stolen or cloned my key fob, and the car would normally allow them to drive off, however my own security system is installed; what is the best way to stop them?

I’l like to have a chat about this before I go for another techstream subscription to work out the finer details, but should that be my best option, it won’t be the first time. (What I’d do for a deadtree version of all the documents... or just a really large PDF.)


I digress.
For traditional vehicles, I’ve seen people put a relay on the line to their fuel pump, so that if they do not enable it before driving off, the car will not get very far, if even start at all. Additionally, should the car be disabled while driving, it would stall, and allow the driver/thief to come to a safe stop, hopefully. This is not something I would hope to do, as my intended system would be disabled by default, needing activation before the car drives off, but it’s worth considering as if anything were to happen and the system were to trigger while the car was driving, I would not want it to risk injury or damage.

As for my Aqua, I have identified multiple potential options, and would like to explore them.

1: Fuel pump
Same as before, but now with the added benefit that the car could drive some distance on electric, should the system be engaged while the car is moving.
Problem is, someone could still drive the car a fair distance on electric from parked with it engaged. Perhaps an option for a safe, post-theft remote killswitch, as even if it is activated while the car is driving, the car would still be safely controllable, as I have done many times when pushing my luck with its range a little too far.

2: Contactor
With a line to the contactor cut, the car’s not doing anything if the Power-on-self-test fails, let alone not having the HV battery itself.
Con is, I’m not sure how happy the ECU’s and inverter would be if the test failed, and how much work it’d be to get them working again.
Good for a one-off, but needing to get it towed to a dealer after just one test would be unfortunate.
Additionally, I suspect that cutting the contactor with the car still driving could do untold damage to the battery, contactor, and inverter. Oh, and probably kill someone

3: 12v line
Problems all around here, the least of which is that a thief may think the car is just flat and try to jump it, mixed with the car needing to be re-enabled before the key would unlock it, throw in the damage done if disabled while driving (unless the car can sustain itself from the 100A output on the inverter, still, if not, getting teleported into a T-model ford, while doing 100MPH, with no airbags or power steering etc, that’s not a wreck I’d want to buy), and, worst of all, having to reset the clock every time I get inside.

4: Some super secrit control line somewhere that Toyota installed for just such an occasion
What can I say, I’m an optimist

I’ve had a poke around the forum and haven’t found any similar discussions yet, but I might not know the right words to search for.
“Killswitch” doesn’t turn up much, spare a thread where I found the following:

After which, the thread died.
Another post suggested

and while I don’t totally understand the meaning of this, I’m guessing it means to cut a line to something so that the car’s power-on-self-test will fail, and the car will not enter READY mode.
Let the car itself handle the locking.

Many such options, the only question now is to find one that would not cause a permanent error code if the car was started without it.
Additionally, it would mean that, if it’s something as innocuous as, say, one side of your headlights, that should it be disabled while the car is in motion, nothing detrimental should happen.
A jumper for an optional feature that was not installed, perhaps?

Anyway, I’m out of ideas, and would be very grateful for any further commentary.
Thanks in advance, and all the best
-Sky

 

I have more than enough contingencies for if they lift the thing and pull it, still, unless they put it in a totally soundproof faraday cage, I’m finding it. Everyone inside or around the car would be permanently deafened, everyone even remotely close would be calling the police, and there’s enough GPS trackers and transponders inside that unless they melted it down into homogeneous slag, I’m finding it.
The point is, I would be able to find it long before they had the chance.
This thread is simply so I can avoid all such contingencies, rendering them irrelevant. I won’t go into further detail as I don’t wish to provide any information usable to circumvent any of my security measures.
Just because it is a possibility that someone with a UFO can fly over my house and teleport my car into a volcano doesn’t mean we should all bend over backwards and do nothing to secure our belongings.
I’ve got the damn thing insured for enough to import two brand new Aqua’s fresh from Japan, that’s besides the point. Some things have sentimental value, that you can’t insure, and for that reason I’m going to give anyone who so much as looks at my car funny a permanent case of tinnitus.
For some of us, it’s not a matter of a cost benefit analysis. It’s “Did I do everything I could, reasonable or not, to secure my car, allow myself to recover my car if the thief had a flatbed, and, if they did have a magic volcano-teleporting UFO, at least deafen them for their trouble?”
If I don’t at least make someone permanently reconsider their life of crime, was any of it even worth it?

I will also add that individual Aquas have been used to transport goods, the theft of which exceed the combined value of every Aqua ever produced, and that people who work for certain agencies would find the notion of any level of avoidable risk being “acceptable”, well, rather aggravating.
Aquas are nice cars. They’re small. Quiet. Discrete. Innocuous.
That may attract a certain type of person.

Finally, $80,000 of repairs on a single car.
You don’t need to tell me I’m crazy. You won’t be the first, and there’s nothing you can say to convince me. You can’t convince someone there’s something wrong with them when they already believe and accept there is.

Mine happens to be pushbutton, out of curiosity I’ll see how well the handbrake does at stopping it on the freeway with the engine still cruising. Drum brakes are cheap, right?
A major concern would be the lack of a failsafe option here. Either require a relay to be engaged to cut the brakes, using power when the car is off, and defeatable by cutting power to the security module, or have the brakes cut when the power is not applied, and thus risk loosing the brakes if the module fails, or power is cut in any path of the circuit. Neither options seem acceptable to me.

 

Ah, a latching relay may be a rather safe way of doing things, there’s plenty of signals that correlate to the car being in READY so holding the latch open with one of them would be trivial.

I believed the car’s regenerative braking was controlled by a position sensor on the brake pedal, and that the car controlled the brake lights and cruise control, along with going into READY, from this signal should it be partially engaged. If this isn’t the case, or there are multiple signals, then that clears all my worries, but at very least I remembered that you’d still have the hydraulic brakes anyway, electrical signals or not.

Between this and the idea for a latching relay, I’m pretty happy with this as a killswitch. If the worst possible thing that could happen in a failure is them loosing the brake lights, that seems pretty good to me.

Edit: Looking at the schematic now, it does appear there is a seperate switch for the brakelight, the only question left is if that is used for READY, or the position sensor. Time to test it.
If it is just the switch used, and the switch directly controls the lights, with the ECU detecting a signal, then it’s still possible to cut the line to the ECU without cutting the power to the lights itself. I’ll have to check the wiring diagram...

 

I was suggesting you’d need something to be both a faraday cage and soundproof, just to be sure.
If any frequencies are getting out, I’m finding it.

There’s certain mistakes in life that you just have to make. It’d be a mistake not to.
I’ve promised not to get too attached to any of my new cars, but they’re all replaceable. This was my first.
Half the point of insurance is to give me something nice and fancy to distract me from what I’ve lost. Really cut down on the grieving stage. It’s hard to be too sad when you’re on a tropical island sipping glasses of “well if you can sort out the problem with the power steering then power to ya”, while crying tears of “why didn’t I just accept the writeoff payout the first time?” while waiting for a new car to be built.
At this point I’m not even sure if I care about the car as much as I’m making it out to be, but trying to make it as unstealable as possible has become somewhat fun.

 

Considering this thread resolved any and all potential problems I have come across thus far, and the only thing left for me to do is play around with some relays then wire them in to one of my tracking modules, I don’t see what potential problems remain at all.
I live in the car theft capital of my country. Every day I see a new burned out car on the side of the road.
Finding and importing a 2015-2017 Aqua, in the trim and colour I like, in mint condition, takes more time in paperwork than I’ve spent on my security system thusfar.
I’m an optimist, in that “If the worst possible thing happens, I’d expect something other than the worst possible outcome, as both the worst possible thing happening, followed by the worst of all possible outcomes afterwards, seems rather unlikely”.
If I make sure the worst possible outcome isn’t that bad, then I’d never need to worry a day in my life.

The benefit is that if someone tries to steal my car, they most likely will either give up when it doesn’t start, or abandon the idea when the 160db alarm doesn’t stop after they disconnect the battery, rather than me having to grab my [redacted]s, chase them through town with my [redacted], eventually [redacted], dragging them out of the wreck, and [redacted] out of them, then having to explain to my insurer what happened. Again.
Having to do so would be most unbecoming of me. I’d really rather not, if it’s all the same with you.

 

Oh I have far more than just the one.
Still, if we’re going to moralise then I’d suggest you don’t just drop into random threads and offer virtually no advice. You mentioned problems with what’s been discussed, care to offer anything further? Actually tell me why a killswitch, something that’s been installed on cars dating back decades, is somehow all of a sudden a bad idea?

If not, then I’m curious why you’re here.
“Spending months wages, tens of thousands of dollars, possibly a thousand hours of labour, on a car? Perfectly reasonable. No issue.
Spending a WHOLE WEEKEND putting some trackers in it? Protecting your property rights? WoooOooOoOoAAAh, looks like someone’s a little obsessed xdxd ”
Such comments are completely without substance and are utterly vapid and meaningless.
Either someone cannot afford premium insurance and as such may not be able to afford the luxury of unprotective property rights, or someone can afford insurance however still believes, on principle alone, that property rights should be protected. To suggest such things are an “obsession” that someone needs to “feed” contributes about as much good to the world as going to an up market restaurant, sitting down for a meal, and spending the entire evening lecturing the people sitting on the table next to you about world hunger.
Or going to a forum for the owners of exotic and luxury sports cars and calling them all obsessed.
89% of people aged 21 to 35 state that their lives have no meaning, and, coincidentally, the suicide rate for that age bracket is skyrocketing, driving down life expectancies for entire nations.
When things like “Property Rights” and “Hobbies”, “Pride in your Possessions” and the like are universally derided, in a society where someone cannot be expected to maintain ownership of something when someone else may wish for it more, when society is on its last legs, barely hanging on by a thread because at least maybe people will still want to go to work to buy fancy shiny things, and you start hacking away at the concept of property rights with a chainsaw, where do you expect the world to go from here?
How much of the year am I supposed to be driving a filthy hire car before it’s justifiable for me to spend a weekend trying to prevent my car from being stolen?
You get the society you deserve.
When you treat crime as something rare enough that it’s worth putting something simple like a killswitch on your car, just in case, then criminal activity is disincentivised. When you treat is as something so commonplace that it’s not even worth trying to reduce your chance of being stolen from, and your only consideration is for a contingency after the fact, then by doing nothing to disincentivise crime, you encourage it.
I’d rather not live in a society like that.
Some maybe happy living in a world without property rights, freedom from crime, individual freedom, rights, personal responsibility, but I’m starting to get a taste of that world, and I do not particularly like it. I am more than willing to fight it. One small step at a time.
And pray tell, if not for hobbies, what the hell else am I supposed to do with my time?
There is little anything anyone in the world can personally produce that cannot be produced elsewhere more cost-effectively. Am I just supposed to consume? Is that it?
Don’t change or create anything, just buy car let car get stolen then buy new car, so long as I never stop consooming, never create anything, never question the idea that everything you can purchase is already the best that something can possibly be, just buy new thing when new one comes out, it’ll have the things that the deranged, obsessive losers added five years ago! Just consoooooooooooooom!

Again, I’d rather not.