Did a dumb

[just-a-scratch]

Did you know that some keys have RFID chips that are needed to start the car? I didn't know that. I like my keys thin and dislike bulky crud in my pockets. So, I stripped down a car key.
When I finished a minor exhaust project not related to the key, the car wouldn't start.
One key starts the car, the other does not.

[VincentMalamute]

@just-a-scratch said in Did a dumb:

Did you know that some keys have RFID chips that are needed to start the car?

yeah, I knew that. I can see myself doing exactly what you did despite knowing that.

I have a Transit with a nonfolding key attached to a very bulky remote fob. I've considered cutting off the key part to slim it down some. I should be OK though because I ordered the van with no security system, not even the passive security which should be the RFID chip,

[sn4cktimes]

@just-a-scratch @VincentMalamute Even if the RFID is required you could just stash the chip in the vehicle... it defeats the security purpose, but then you don't have to haul it around.

[aremmes]

@just-a-scratch I remember in the 1990s GM used to put chips on their keys on a little plastic carrier inserted into the shank, but I think those worked through electrical contact. Key fobs have RFID as a backup for starting the car when the fob's battery dies.

[Boxer_4]

@aremmes Specifically, the chip that VATS used was a resistor. There were a set number of resistances that were used, and the car computer would know what resistance it needed to know the key was correct. Bypassing the system required determining the resistor on the key, and soldering in the correct resistor into the system to trick it. Good thing it was easy to bypass because it failed often.

[Just Jeepin']

I let a stranger drive my LJ once, saw him walk to his YJ and started a discussion about our Jeeps.

I handed him the keys while chatting with his girlfriend (what can I say, I much prefer talking to women than men) and he would crank it but it wouldn’t stay started.

Thankfully, of course, it was just the wrong key, but given how flaky the LJ has always been I assumed it had managed to break again.

[Chariotoflove]

@just-a-scratch said in Did a dumb:

Did you know that some keys have RFID chips that are needed to start the car? I didn't know that. I like my keys thin and dislike bulky crud in my pockets. So, I stripped down a car key.
When I finished a minor exhaust project not related to the key, the car wouldn't start.
One key starts the car, the other does not.

Oh, uh yeah, that’s a problem. You can get a new one made though if you need. You only need one that can start the car. You can still make as many door lock keys as you want.

[Italia]

@boxer_4 when I worked for a locksmith we had a tiny box you poked vats keys into and a number showed up on the screen to tell you which resistance blank you needed. We charged a ton of money to duplicate those because we could. This was before keys got real crazy in the 2000's

[RallyDarkstrike]

@just-a-scratch Yes, they make far more sense to me than modern 'keyless fob' tech that takes 30 seconds, some freely available programming (if you know what dark corners of the web to look into) and some cheap Amazon parts to spoof and steal a car with.

Because with a chip key you need to defeat the physical key somehow AND the RFID chip.

[SamV8]

@sn4cktimes I'm not sure about every rfid for car keys but the ones I have come across are very short range that they need to be by the ignition keyhole to work so if you were to just leave it in the car it'd need to be stuck near the keyhole

[sn4cktimes]

@samv8 Pop the dash/column cover and tape it to the backside maybe?

[VincentMalamute]

@sn4cktimes
@samv8 said in Did a dumb:

I'm not sure about every rfid for car keys but the ones I have come across are very short range

That makes sense. The RFID keycards for work need to be within centimeters. I doubt the ignition security has a large enough antennae/amplifier to work beyond an inch or so.

[Urambo Tauro]

@boxer_4 said in Did a dumb:

@aremmes Specifically, the chip that VATS used was a resistor. There were a set number of resistances that were used, and the car computer would know what resistance it needed to know the key was correct. Bypassing the system required determining the resistor on the key, and soldering in the correct resistor into the system to trick it. Good thing it was easy to bypass because it failed often.

I had a '92 LeSabre with that resistor pellet system. I remember when it started acting up, and there was some kind of timeout that let me start the car if I waited (three?) minutes. IIRC, it only disabled the starter trigger circuit, so you could still jump the main solenoid contacts if in a hurry.

[Jb boin]

On VW cars at least, the RFID chip is used for the immobilizer so if you flash your ECU with the immobilizer safety disabled you can start the car without a chip.

If you want to duplicate your still working key, you can buy a RFID reader/programmer tool that can listen to the signal sent from your working key then r program it on a blank programmable transponder.
You can find such tools for about 100$.

Or program your car to accept a new key/transponder but it's specific to the car and sometimes can be quite tricky to do (especially on newer cars).

[HFV_Junkyardin]

@just-a-scratch I learned this when I tried to get a spare for my 2001 Civic. I just went to the hardware store and got a copy cut for 3 bucks. That one didn’t start the car. Would have had to get one with a chip at the dealership for 150 bucks. That’s probably cheap compared to modern keys though.

[koawaft]

@boxer_4 I remember having to do this to my Grand Prix! I felt like such a bad ass breaking out my multireader and going to Radio Shack and fixing it myself. 20 year old me was real impressed with himself. 43 year old me would be much more afraid of setting off the airbag.

[MybirdIStheword]

@just-a-scratch for some reason I always thought those "chipped" keys had the chip built into the key blade itself, used the conductivity of the key to work. RFID seems a little extra in that function

[BaconSandwich]

@hfv I remember getting a spare key cut for my 2001 Civic as well. Got the chipped version, and I think it was around $100, but that was also 13 years ago.