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...do not break or lose your last key. A Fiat with the alarm activated and no valid key will melt the BCM... I'd likely bypass all the security by embedding the last working fob in the car and driving and locking the car with non transponder keys.
1) Can you avoid BCM melting by disconnecting the 12V battery?

2) Does anyone know how close the transponder needs to be, in order to start the car with a non-transponder key? For example, could it be hidden under the hood, or in the back of the hatch?
 

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Thanks.

1) I meant get a cheap non-transponder copy made just in case, so that after loosing your only transponder, you could open the door with the copy, alarm sounds, pop hood, disconnect 12V. Still possible BCM destruction?

2) In this scenario with one remaining transponder key, I guess you could just USE that one to start & drive, then always use cheap non-transponder keys to lock it in the car, hidden in the glovebox, under a cup in a holder, under a seat or mat, etc, etc, etc...
 

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Great! Thanks! So that's a solution IF you don't mind sacrificing security to save $280 on a spare transponder key:

If you only have 1 transponder key, to avoid frying your BCM if you lose that one, glue it inside the steering column cover & use cheap non-transponder keys to lock, unlock & drive.
 

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A Fiat with the alarm activated and no valid key will melt the BCM, permanently disabling the car. The car will have to be towed, the BCM replaced, and new keys precoded and programmed to the new BCM.
Hold on! So if I'm in the grocery store & someone breaks my window to steal a laptop or something, & they open the door to grab it, my car is immobilized & I'm stranded with around $1,000 damage?! (towing + two $280/keys + BCM + window)

if you unlock twice, it doesn't set off the alarm.
I just tried that with one of my 2 functioning transponder keys on my 2013e with all software updates & it set off the alarm & wouldn't shut off without the push-button:

  • I tried unlocking twice before opening the door & the alarm activated.
  • I tried unlocking 3 times before opening & the alarm activated.
  • I tried unlocking, opening, unlocking.
  • I tried unlocking, locking, unlocking, opening.
 

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This seems to be a very important lesson, learned the really expensive way by some. ga2500ev or anyone else please correct any of the following:

If at any time you are down to only one transponder key & you don't get a backup for about $380, losing that last key will cost about $1400 + towing to a dealership.

To avoid those costs you could get 1 or more cheap non-transponder copies, glue the transponder key inside the steering column cover, & use the cheap copy to lock/unlock/start. The alarm won't arm, & it would be possible to hotwire, but a thief won't know that, so they'll probably already be prepared to just slim-jim & tow it (normally needing to pop the hood to yank a 12v terminal to shut off the alarm).
 

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Well there ARE some classic Toyotas that might be worth it, like maybe a 2001 MR2 Spyder. I wonder why Fiat is still using a system that Toyota dumped 15 years ago.

My friend's new Hyundai came with an extra little fob attached to the key, with a scanner code, but probably also a transponder. The salesman said do NOT lose it, or it would be VERY expensive to get a replacement key!
 

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So if the little paper scanner code sticker wears off you're screwed!? That seemed so crazy that I figured it must have a chip in the plastic.

Anyway, in the realm of "misery loves company", it's nice to know it's not just Fiat that can be a pain if you lose a key.
 

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With Tesla, your phone's bluetooth can be your key for unlocking & then pushbutton starting. I think some models have or are working on facial recognition unlocking.

What I meant about Hyundai was that since it's crazy to be screwed by a little paper tag wearing off, I figured the plastic it was stuck to had a chip in it, that could be scanned to make a replacement transponder key.
 

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Yes, the car needs some kind of radio transmission from the transponder to start along with the physical key. That's the main (only?) point of the transponder.
 
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