this module or sensor fits in a spot in between the left and right sun visors just over the rear view mirror. don't have a clue what it is, it never comes "on" on the back end where the contacts are on the circuit board are the KF9 it is about the size of a old fashion butane square lighter. it just slide in and plugs in there, but for what? I cannot find any info on it. see pics, in my Pioneer 1990 cherokee

 

EJECT button......

 

Receiver for keyless entry.....

 

my 91 X J has the same thing between the visors only mine is round and looks like a security camera that you would see on the ceiling of Walmart I kind of thought the feds were spying on my Jeep

 

I thought the keyless entry began in 1993. For 93-96 models, the dome is the receiver for the infra-red remote entry. The remote only works close to vehicle and pointed at receiver. Not like today's radio frequency remotes.
Key Fob part #56009031
Sold all 5 of the ones I had.

 

I thought maybe part of an alarm system. but I hope not
I had enough of malfunctioning alarms in my 94 Laredo.
I have a Haynes maual for the Jeep but there is no mention of it.
that I could find. Thanks for the ideas!