Chip or radio in modern car keys as part of anti-theft system?

I am curious as to how modern car keys are made these days. It seems that the new 2015 Mitsubishi Mirage has a special key you need to get from the dealer.

Since I am the outdoorsy type, I am pretty hard on my stuff. I can see getting caught in a downpour with my car keys. I know the ones with the keyless entry in the heads are expensive to replace so I had a key made from a blank for $2, figuring this will be the only key I carry with me when I am outdoors and leave the others hidden somewhere safe.

The guy at the hardware store told me right off that this key will open the doors but probably not start the car. I said that is fine as I really just need to get into the car and don’t want to ruin the electronics in the other key of they get wet, etc.

Yep, he was 100% correct. I can get into the car with the spare key but it will either crank and not start or start for a second and then die. Apparently there is a chip of some sort in the factory keys that communicates with the car. There is only one keyhole on the driver side door for the entire car so obviously this is just a backup for getting in.

What happens if the battery in the key head dies? Will the car not start? I know some chips require power while many door access systems at buildings do not. The signal sent from the door energizes the device just long enough to let you inside the building.

This is a cheap car as has been discussed in great detail in the HUGE thread about the HUGE sale on them so cannot imaging it being a very complicated system compared to some on higher end cars. Even the “deluxe” model of this car has a push button starter that only works when a fob is within a certain distance. There is no mechanical component to the system.

How common is this in new cars to have a chip in addition to a mechanical key?

The battery in the key is for the keyless entry system, the “chip” in the key is actually a resistor. Similar to the system GM introduced in the mid 80’s and as far as i know it’s pretty much universal these days. The dealer might be able to get you a valet key which will open the door and start the car but at a higher cost.

Many new cars now use an RFID system which is powered by the inquiry signal the car sends to see if a matching key is present. So even if the battery dies, the car will still start. Most cars with keyless entry/ignition have a hidden key in the fob that you can pull out to manually unlock the driver side door if the transmitter battery fails.

As to getting the key wet, you will most likely not harm the chip - I’ve accidentally sent mine through the wash a time or two. All of the electronic circuitry and the battery are buried inside a waterproof shell mounted on the inside of the keyfob.

In my Pontiac, I have my spare remote in the trunk, then have a spare $2 key hidden. So I can get into the trunk with the key and then get the remote (with the expensive key) to start the car. With the Acura I’m out of luck. If you don’t have the remote or the car battery is dead, you aren’t going anywhere. Not a good car to take out on the lake ice fishing where keys get lost.

What’s with this statement that the key contains only a resistor? I know for a fact that the key contains some complicated electronics that does encryption of the data sent to and from it.

I’ve heard tale with some electronic key designs it is possible to renew a worn out key by extracting the chip then glue it to a new key that works but hasn’t a chip.

I see. I figured it was something like this. The RFID chip would probably also keep working if it got wet. They encase those in resin that is water tight. Either way, I plan to use one of the spares when outside.

The car did act funny the first time when I started it with the factory key after using the spare. The starter had a noticeable delay and it took longer to start. The rest of the starts today were 100% normal.

I guess you could just put the old key on a ring next to a blank and see what happens. I wonder if the car would stall if you removed it from the proximity.

If one is camping or hiking if you have put your keys in a ziplock bag it won’t matter if it rains. Or is that too simple?

How “modern” is your car?
I had a physical copy of my 2005 key made to keep in my change pocket just to unlock the doors if I lock my main key inside. It won’t start the car, but it will let me in. Because Home Depot policy doesn’t allow copying keys with chips in them, I had to go to three Home Depots and find an old guy that understood what I was doing in order to get it made.

Why did I do this? Because a key with a chip (no fob to unlock the doors, just a chip to start the car) would have cost me $80. One with a fob would have cost $145. The physical copy only cost a few bucks.

With my luck, a ziplock bag would leak. The $2 key copy seems to the the simple solution. It lets me inside the car and then I have access to the real key.

I do always carry a large ziplock bag in my camera case so I can try to protect my camera if caught in a downpour.

You have to love the policies of large corporations. I recently had a leaf blower get caught in a fire. I was able to save it and amazingly the thing starts right up but it really just a good running engine with a melted plastic shell surrounding it. I posted a review on the manufacturer website saying how I was amazed because it still runs after all it has been through. About half my review was flagged red for “legal violations”. I guess they would have rather me just let it burn. Anyway, I don’t think I will bother to even resubmit a “sanitized” review. I remember seeing a report that a certain chainsaw manufacturer had a warning not to stop the chain with your genitalia. I think this is a great idea. This way the stupid people cannot reproduce and they win a Darwin award without actually dying. The cannot produce offspring and they made it this way in a unique way so they at least deserve “honorable mention” in the Darwin awards.

You have to love lawyers and the legalistic nature of large corporations. In owning my small business I have had to deal with some undesirable folks. There is no sanitizing my policies and I have had to let a few people know that they will either back off or be shot.

Hm, you’d think the manual transmission would be enough of a theft-deterrent. . . these days. :smile:

I’ve heard that the car doors will not lock if it senses the “fob” is inside the car, preventing you from locking yourself out of the car. Haven’t tried it myself yet though.

I think pretty much ANY new car nowadays has some variation of a chip key (or fob) which communicates with the car.

The wife’s Saab has a key that will not start the car if the key’s battery is dead and the car will TELL you when the battery is getting weak on the driver info display. So I doubt this one has an RFID chip since that gets power from the radio that queries it. And this car is 15 years old and was a GM owned company when the car was built. A new key cost about $180 or so 12 years ago when we lost one of the keys.

I guess most home improvement stores/hardwares as well as Wal-Mart sell kits where the owner can pair keys themselves. I may research this on the Mirage Forum and see if it can be done by the owner.

Also, I was told this is now standard on all new cars with the exception of the Nissan Versa base model. I guess they really did go cheap on this one!

There is a reason why the chip keys sold in hardware/improvement stores cost so little. They do indeed have a small battery in them (unlike the keys from the manufacturer, dealer, or locksmith).

When that small battery in those keys goes dead, the car won’t start.

Huh? every car I’ve had with a remote lock/unlock has a battery in the key fob. From the manufacturer.

cwatkin: “I was told this is now standard on all new cars” ? what is now standard?


Hi BillRussell:

Huh? every car I’ve had with a remote lock/unlock has a battery in the key fob. From the manufacturer.

Sorry if I was not clear. I wasn’t referring to the key fobs, which all have batteries.
I was referring to the “chip keys” themselves.

The aftermarket hardware/improvement store variety that cost much less than the dealer/locksmith has a battery in the “chip key” itself.

Joe: still confused. What you mean by “chip key”?
My key or key fob, is a key with a plastic thingi attached with battery and electronics inside.