I can't start my 2008 Jeep Grand Cherokee with either key fob. Once I got a "Service Security Key" message. Another time I got the "Key not programmed - Damaged key" message. What do I do? Take the key fobs to the dealership or do I need to take the Jeep and the key fobs to the dealership? And is there anything I can do to fix this?

Generally, I warn against bypassing immobilizers. You need the key fob for the doors though. The door fob is part of the security system.

https://itstillruns.com/reset-grand-cherokee-reset-antitheft-7492453.html

There are various ideas here

https://www.google.com/search?q=2000+jeep+grand+cherokee+immobilizer+reset

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Keyless Remote Key Programming Procedure:

1. Insert first programmed key into ignition and turn ignition switch to ON for 5 seconds. ...
2. Turn ignition switch to OFF and remove key.
3. Insert second programmed key into ignition and turn ignition switch to ON. ...
4. Turn ignition switch to OFF and remove key.

More items...

Key Fob Keyless Entry Remote for 2008 Jeep Grand ...

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GOT OPTION "ENTER AND GO"???????????????
did you use both FOBS. car came with 2, try using both , one at a time and not both near car as SAME time. ever.

mines turned off for ever,
i never armed it.
so page what.
wow 6 owners manuals, 4 for Uconnect, wow. pain.
page 22. read that?
sure.
is this not clear ,quoted
The Vehicle Security Alarm is designed to protect your
vehicle; however, you can create conditions where the
Vehicle Security Alarm will arm unexpectedly. If you
remain in the vehicle and lock the doors with the RKE
transmitter, once the Vehicle Security Alarm is armed
(after 16 seconds), when you pull the door handle to exit,
the alarm will sound. If this occurs, press the UNLOCK
button on the RKE transmitter to disarm the Vehicle
Security Alarm. You may also accidentally sound the
Vehicle Security Alarm by unlocking the driver's door
with the key and then opening the door

good luck deciphering this page, wow.!
page 23 is NO ENTER AND GO', OPTION.
Either press the UNLOCK button on the RKE transmitter,
pull on the front driver or passenger door handle (refer to
"Keyless Enter-N-Go" in "Things To Know Before Starting
Your Vehicle" for further information) with a valid
key fob in range, or press the Keyless Enter-N-Go Start/
Stop button (requires at least one valid Key Fob in the
vehicle), or insert a valid Key Fob into the ignition switch
(if the Start/Stop button is removed) and rotate it to the
ON/RUN position.

END QUOTES FROM YOUR GUIDE.
if all this fails get jeep to fix it. (the magic is broken so...)
or ask them to explain, page 23 , in non GREEK..

Check this out, not the right year but i doubt that the procedure isn't very different.
How To Replace Jeep Grand Cherokee Key Fob Battery 2014 2015

To free key fob from the ignition, disconnect the negative cable to the battery for 2 minutes. This will do a hard reset on the electronics. Key fob is free and back to normal.

Try not using the fob at all open the door with the key. And start the jeep if it works without issue then its the fob. If its still not working correctly remove the battery from the fob and try again(since if it was damaged could be sending the signal for the panic button) the next step is the key try your spare security key can become worn and cause issues with the antitheft system. After that it only leaves computer problems and those can get spendy

Hello, This is not a Brand I normally service. If you have a Dash light indicating that you have a "Security Lock-out" then I would look at your Owners' Manual for instructions on Reactivating the system.

You can call a Jeep Dealer and ask basically the same thing. "How do I get my Jeep started once the Security system has been activated?".

Some of the Security systems have their own Weird procedures like hitting the doorlock button 3 times after the Keyswitch has been turned 3 times within a number of seconds.

Your Battery could be bad in the Jeep and this is sometimes picked up as attempted Theft when the wiring Voltage fluctuates. The Security system views the Voltage fluctuations as Wire Tampering.

electronic key on 2008 jeep cherokee says key damaged or key not programmed. car won't start. some things work but radio won't come on. etc..

When my 1995 Jeep Grand Cherokee will unlock the doors but not deactivate the security system it is always time to change the battery in the key fob. Don't order a new fob, just pry the fob open (carefully) and replace the battery. I buy mine from Batteries + and they cost like $.80 a piece + tax.

This sounds like a bad chip in the key, try a spare key, if it starts with spare key then key is bad, if it doesnt start then you will need reprograming