Programming Smart Keys

flynz4 · 12-17-2005, 11:23 PM

I just bought my daughter a Prius and decided to get one for myself as well. Is there any way that we can program both cars work with all 4 smart key fobs?

I guess another way of asking: Is the key fob programmed for a specific car code... or is the car programmed to recognize more then one key fob code?

I am hoping the later. I would like to be able to operate her car when necessary without carrying (and buying) a key fob for her Prius.

/Jim

**efusco** · 12-18-2005, 12:01 AM

Quote:

Originally posted by flynz4@Dec 17 2005, 10:23 PM
I just bought my daughter a Prius and decided to get one for myself as well. Is there any way that we can program both cars work with all 4 smart key fobs?

I guess another way of asking: Is the key fob programmed for a specific car code... or is the car programmed to recognize more then one key fob code?

I am hoping the later. I would like to be able to operate her car when necessary without carrying (and buying) a key fob for her Prius.

/Jim

[snapback]175098[/snapback]

some smart people have theorized that this is possible and this question has been asked before. But to date I have not heard from anyone who's actually succeeded and the concensus from the dealers seems to be that they don't know how to do it.

I don't think it is possible, personally, but readily admit I could be wrong.

In any case, if it can be done it must be done by the dealer with all fobs and all cars present....

DanMan32 · 12-18-2005, 02:12 AM

I believe it can be done, though some dealers may insist it isn't but I would question their knowledge on the matter.
Programming a fob with SKS is tricky, as the instructions in the repair manual is pretty unclear, and the supplemental TSBs don't make it much better, though they help some.
With SKS, the SKS, Imobilizer and remote functions all have to be registered separately, though the SKS and remote may be using the same registration sequence.

The registration is very much like a rolling code garage door opener. With such an opener, you press a learning button on the opener, then you press your new remote and the opener learns the sequence of that remote and stores it in one of its slots.
The car can register 4 fobs if you don't have SKS, and 5 if you do. I don't think the fob is specific to the car.

However, you also have to consider the manual key for emergencies. 2 of your fobs will have the mechanical key keyed to one car, the other 2 to the other car. I would suggest having a plastic credit card key made for each car for each of you and rely on that instead of the keys in the fobs.

galaxee · 12-18-2005, 02:22 AM

the fact that it's rolling code would make this hard.

after using a double-programmed fob on one car, it would be out of sync with the other car. you could use the mechanical key to open the door, then pop the fob into the dash to re-sync the smartkey and use it on the second car, but you'd have to repeat that procedure every time you switched cars.

we haven't tried this, this is all based upon his knowledge of rolling code systems and what he's seen from prii that have come into the shop.

plus, the dealer will charge a ton of cash to program all this. partly because they probably have no idea where to start, and because it will take a long time to get it all straightened out. not to mention really irking the guy who has to do it (says the tech husband

)

DanMan32 · 12-18-2005, 02:30 AM

The car will look ahead up to 255 iterations of the fob's code. Past that, the car loses pairing with that fob. When the car hears from a fob, it checks the code it received from the fob to the codes stored in each of the 4 or 5 slots, plus the next 250+ codes that could come from the fob, starting with the codes in the 4 or 5 slots.

So, if you use 1 fob exclusively with one car, and the other car doesn't hear from it for a long while, then it may become useless with the 2nd car. This could also happen if your kids get ahold of your fob and press the buttons 256 times out of range of the car.

galaxee · 12-18-2005, 02:31 AM

yep, he's seen a few cases, although rare, when someone has something pushing the button in their pocket all day and the key is no longer smart.

that's when they stick it in the dash and it regains its IQ, so to speak...

[edit] he didn't know exactly how far ahead it looks, that's great info to know. thanks.

DanMan32 · 12-18-2005, 02:42 AM

Quote:

Originally posted by galaxee@Dec 18 2005, 03:31 AM
that's when they stick it in the dash and it regains its IQ, so to speak...

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Hmm, I hadn't thought of that. The short distance RFID is static, or if it is rolling code, would only be incremented when the car reads it in the slot. So, if the fob lost remote/smart pairing, it could be authenticated by the RFID, and automatically re-paired.

255 is a ballpark. The chip that is commonly used with rolling code devices has 255 code look ahead. Toyota could have used a different implementation.
If you ever want to test this out, and have lots of time on your hands, try it, pressing the button more and more often out of range of the car between testing if the car still recognizes it.

galaxee · 12-18-2005, 02:43 AM

Quote:

Originally posted by DanMan32@Dec 18 2005, 02:42 AM
If you ever want to test this out, and have lots of time on your hands, try it, pressing the button more and more often out of range of the car between testing if the car still recognizes it.

[snapback]175195[/snapback]

thanks for giving him THAT great idea...

DanMan32 · 12-18-2005, 02:49 AM

Walk into the living room,. press, press press, back to the garage. Works. Back to the living room, press, press, press, press, back to the garage. Still works.
....
5 hours later,
...
Back to the living room. 250 presses, back to the garage, still works.
Do you accept me now? Good. Do you accept me now? Good.

galaxee · 12-18-2005, 02:50 AM

i can hear him saying it now....

12-18-2005, 02:22 AM	#4
galaxee mostly benevolent Join Date: Mar 2005 Location: MD Posts: 9,810 My Car: 2005 Prius Model: N/A Package: #5 Thanks: 0 Thanked 331 Times in 85 Posts Friends: 27	the fact that it's rolling code would make this hard. after using a double-programmed fob on one car, it would be out of sync with the other car. you could use the mechanical key to open the door, then pop the fob into the dash to re-sync the smartkey and use it on the second car, but you'd have to repeat that procedure every time you switched cars. we haven't tried this, this is all based upon his knowledge of rolling code systems and what he's seen from prii that have come into the shop. plus, the dealer will charge a ton of cash to program all this. partly because they probably have no idea where to start, and because it will take a long time to get it all straightened out. not to mention really irking the guy who has to do it (says the tech husband ) __________________ black 2005 prius, a few mods that make me happy

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12-17-2005, 11:23 PM	#1
flynz4 Senior Member Join Date: Dec 2005 Location: Portland, OR Posts: 263 My Car: Model: Package: Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	I just bought my daughter a Prius and decided to get one for myself as well. Is there any way that we can program both cars work with all 4 smart key fobs? I guess another way of asking: Is the key fob programmed for a specific car code... or is the car programmed to recognize more then one key fob code? I am hoping the later. I would like to be able to operate her car when necessary without carrying (and buying) a key fob for her Prius. /Jim

12-18-2005, 02:12 AM	#3
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Model: Package: Thanks: 0 Thanked 7 Times in 7 Posts Friends: 0	I believe it can be done, though some dealers may insist it isn't but I would question their knowledge on the matter. Programming a fob with SKS is tricky, as the instructions in the repair manual is pretty unclear, and the supplemental TSBs don't make it much better, though they help some. With SKS, the SKS, Imobilizer and remote functions all have to be registered separately, though the SKS and remote may be using the same registration sequence. The registration is very much like a rolling code garage door opener. With such an opener, you press a learning button on the opener, then you press your new remote and the opener learns the sequence of that remote and stores it in one of its slots. The car can register 4 fobs if you don't have SKS, and 5 if you do. I don't think the fob is specific to the car. However, you also have to consider the manual key for emergencies. 2 of your fobs will have the mechanical key keyed to one car, the other 2 to the other car. I would suggest having a plastic credit card key made for each car for each of you and rely on that instead of the keys in the fobs.

12-18-2005, 02:30 AM	#5
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Model: Package: Thanks: 0 Thanked 7 Times in 7 Posts Friends: 0	The car will look ahead up to 255 iterations of the fob's code. Past that, the car loses pairing with that fob. When the car hears from a fob, it checks the code it received from the fob to the codes stored in each of the 4 or 5 slots, plus the next 250+ codes that could come from the fob, starting with the codes in the 4 or 5 slots. So, if you use 1 fob exclusively with one car, and the other car doesn't hear from it for a long while, then it may become useless with the 2nd car. This could also happen if your kids get ahold of your fob and press the buttons 256 times out of range of the car.

12-18-2005, 02:31 AM	#6
galaxee mostly benevolent Join Date: Mar 2005 Location: MD Posts: 9,810 My Car: 2005 Prius Model: N/A Package: #5 Thanks: 0 Thanked 331 Times in 85 Posts Friends: 27	yep, he's seen a few cases, although rare, when someone has something pushing the button in their pocket all day and the key is no longer smart. that's when they stick it in the dash and it regains its IQ, so to speak... [edit] he didn't know exactly how far ahead it looks, that's great info to know. thanks.

12-18-2005, 02:49 AM	#9
DanMan32 Join Date: Aug 2004 Location: Tampa Bay, FL Posts: 3,775 My Car: Model: Package: Thanks: 0 Thanked 7 Times in 7 Posts Friends: 0	Walk into the living room,. press, press press, back to the garage. Works. Back to the living room, press, press, press, press, back to the garage. Still works. .... 5 hours later, ... Back to the living room. 250 presses, back to the garage, still works. Do you accept me now? Good. Do you accept me now? Good.

12-18-2005, 02:50 AM	#10
galaxee mostly benevolent Join Date: Mar 2005 Location: MD Posts: 9,810 My Car: 2005 Prius Model: N/A Package: #5 Thanks: 0 Thanked 331 Times in 85 Posts Friends: 27	i can hear him saying it now....