Diagnosis "91 Liberty Help

[91ej22x8x]

Hi fellow liberty owners, im only new to this site so ill give a quick and boring introduction...
bought a 91 lx liberty (fwd) didnt know much about it when i was going to have a look at it...
so i get to this guys house in a tyre kicking kind of mood, started the car and fell in love instantly, paid 600 for it so it was cheap as but i
had no idea so much could go so wrong so quickly
long story short about a year down the track i end up with a dead car looking for a new motor, found one, ripped the old one out and stripped it to the block
then dropped the new one in...
so here i am today ive had the secondhand (new to me) motor in for about four months now and not had a problem with it as knowing how difficult
leaks and certain other things like timing belts are to repair while the motor is in the car i did pretty much everything externally to the motor i could before i dropped it in
just like gaskets plugs belts pulleys seals basically evrything i could get to without having a full rebuild on my hands as i didnt really have the money at the time
i was driving a commodore, not only a commodore but an auto one and it was slowly killing me and i needed a cheaper car to run petrolwise.

so im driving on christmas day and pop... up comes a red light, i thought it was the handbarake light so i slightly lifted the handbrake and dropped it back down but no it was slightly different, its the same little circle with the brake lines around the circle but an exclamation mark in the middle...
does anybody have any ideas on what would bring that light up or does anybody know if the 91 model libertys have a diagnosis port or anything of that sort?

would really appreciate the help guys cause im stumped for ideas on what that warning light even means as it has no brake wear sensors or anything like that, brake fluid is fine, all basics levels and pressures are ok...

[Dropz]

check your bake fluid level, and the plug on the side of the master cylinder. it may be low in fluid or have a dirty connection on the plug.