How to disconnect the antitheft device on my 1994 grand jeep cherokee

Engine stall or RPM fluctuates at idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

unplug the alarm. had the same problem, had to install a new alarm. problem solved

antitheft system fitted use remote controll to reset antitheft system

Code 12 on any Chrysler or Jeep vehicle simply indicates the battery has been disconnected. Most of the time this code is induced when someone has disconnected the battery as a means to clear trouble codes. This code will clear itself after several successful starts

Disconnect negative battery cable, remove wire harness, Pull clip out with needle nose, then Use a socket and carefully remove the sensor.
You can go to autozone.com and register for full free online repair manual for you Jeep

some alarms have kill switches, but most of them prevent the car from even starting. i would consider strongly getting the remote for the alarm or Completely disconnect the alarm module.

Is Is your battery up to par? If so, Check the ground cable and hope its not the starter.

Need more info. Does it turn over and not start? Does it not turn over? Have you tried to jump start it?

in the 1994 jeep the anti theft device can be over riden by using key lock/unluck back hatch open and close, then start engine as usual. each time u lock or disconnect battery u must do it again.