2000 jeep grand cherokee

If the car has gray key it has a chip in the key so you will need an immobilizer bypass you can use a 555c instead of the 556u, the 555c works without loosing a key,  you just need 2 keys to program it.  The 455j control sthe lock so you will need both.  But I believe that you can use a d.e.i part xk531 Im pretty sure it does door locks, immobilizer bypass and some other things. 

Dittoes on what fcss said. Also Bypasskit besides carrying the XK531 has numerous other options for that car depending on whether you want to to door lock interface, immobilizer bypass, or both.If you're installing it yourself I'd probably suggest avoiding the 555C - it's harder to position correctly than other transponder bypasses.C Renner's Auto Electronix

My service is cheap, quick, and good - pick any two

I agree with chriswallace. The 555C is/was a piece of crap, and has wasted a lot of my time. Incredibly poor design, using a little (and very fragile) pellet you must move around, swear, and move around again over and over. If you have patience, and it's all you have on hand, it does eventually work, though.

really we only use the 555c on those cars it take a few more minutes but it works fine for me, its  not that hard to place it on the key cyclinder.  I know  a 556u is way eaiser but it seems like no body wants to give up a key. 

fcss, if you get a chance you should look at the PKU-CH. It's got a ring antenna instead of the pellet, which makes all the difference in the world in getting it to a workable position. Also, for 2nd gen Sentry Key, the PKUCH2X has the same ring antenna plus a built in output for the starter mux wire.C Renner's Auto Electronix

My service is cheap, quick, and good - pick any two

I will check it out thanks

If the 555c was similar to a unit they made for Ford and Toyota/Lexus bin it it's a waste of time, also re the vehicle.  Didn't that have simple pos locking? If one wire resistive, I always got out the lock switch and measured either side with a DMM, then shoved those values on the lock and unlock (relay driven only) wires from the alarm unit.

Howie, I think you're referring to the 555F bypass for 1st gen transponder equipped Toyota, Ford, Lexus. All the drawbacks of the 555C with the additional fun of Ford's super low power antenna rings that you can't get to see the transponder. The U.S. spec Grand Cherokee is unique for a Chrysler product in not having the resistor multiplex for the doorlocks...it's got driver's lock motor outputs at the driver's door module, all the other lock outputs at the front passenger's, and Class II data(I think that's what Chrysler used) between those modules and the BCM. Additionally the key cylinder doesn't do anything lock-wise. Only options are relays in each front door, a data interface, or hacking the inside of the lock switch.C Renner's Auto Electronix

My service is cheap, quick, and good - pick any two

Yes Chris I am, what a piece of doodie! Thanks for the upgrade, Jeeps have had (Code-Alarm?) factory alarms here since '98 and I haven't done any alarm work on them since late 90's, all I remember was to pos drive the 2 relays in an under dash relay/fuse unit box. "Ain't done the course" on newer stuff!