if it is a UK car, the module was fitted at the docks on import as an upgrade to the standard central locking. It adds immobilisation by storing the remote signal as recognition that it is legitamately being opened. If the module is faulty it will allow unlocking but after two seconds of running will cut out (due to communication between modules and the PCM being told to disable the fuel pump module)
you can send the modules back to may and schofield for repair is the simplest option. (Not sure why 'repair' doesn't seem to be an answer on here, has no one thought of it). After 10 years as a jeep master tech this is the most reliable fix, after market repairs can add in their own issues, and then they become a nightmare to trace.
Mark, August 2010
