J
so the little x looking chip is gone out of key/tether but engine still revs up normally, why?
08 xp chip missing in tether,still runs!
- Thread starter jrddillon
- Start date
1
The chip is actually in the rubber cap itself connected to the middle metal contact and the outer contacts around the inside edge of the dess key. The little metal insert "X" is just a spring loaded device to help make sure the key is in good contact with the dess post and is not needed to work, it justs assists so there is less chance of getting a bad key error.
W
What kind of chip are they using? It's obviously a one wire device, probably a DS2433, something with a little eeprom space. I guess it could just be a DS2403, with a unique id.
1
I was testing some at work and they all have a different resistance value so I wonder if it is just a simple resistor circuit and the computer is programmed with that value?
J
That explains it, I have had a bad key error for two seasons, told dealer every time I took sled in for recalls and clutch crap that I have to start sled 2 or 3 times before it stops beeping, now I need a key and recoil,with out waranty.
W
Nope, from what I understand, people with two XPs can get both tethers programmed to work on either machine. It's got to be a Dallas one wire eeprom. Put a scope to it, and I can read it for you. Scope should be int the 1 ms per division scale, or so.
It appears you program your DESS to accept up to 8 different keys (tethers). So, your tether has a permanent ID, and the snowmobile's electronics, will accept up to eight different IDs.
http://www.dootalk.com/forums/index.php?showtopic=11844
The resistance, is probably just the pull resistor, for the communications port. Open collector I believe. Believe me, a one wire device is like 50 cents, electronics to measure resistance is much more.
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1
took a key apart today, had a ds2401 chip in it.
W
Cool, that's the oldest chip, originally made by Dallas Semiconductor. Simple 64 bit unique ID. Actually, the last 8 bits are a CRC. No eeprom in that chip. We use lots of them. The company actually never makes the same key twice, SkiDoo must have bought a whole series of numbers. So, they put the 64 bit ID in the engine computer, and it will only run right, if that code is passed down from the DS2401. Would be easy to copy keys, and make a duplicate key, using a AVR 8 bit micro. But, unless you got your hands on the key, to copy it; there's no way to make a universal key. UNLESS, skidoo has a universal number series they use. Now that would be interesting. I bet they do.
The way a one wire works is pretty simple. The pull up resistors power the part up and a capacitor in the part keeps it running during communications. Then the master (the engine computer) pulls line low and releases it. But, the DS2401 holds the line low. It hold it low for a short time, if it's a 1, and holds it low for a long time, if it's a high. Then after a little while, the master pulls the line low again. and the DS2401 holds the line low again. After 64 times, you know the entire number.
C
Wade....YOU ARE A HUGE NERD! 
Extremely good info though!
Extremely good info though!
