You mean the light on the little box? No, It doesn't come on with the brakes. In fact, it randomly flashes while I drive down the road. Sometimes, when I open the door and get in, it's flashing merrily away, other times there's nothing when I open the door. Sometimes it starts flashing after I've been driving for a while, other times it never starts flashing at all.

There's no rhyme or reason to why the light goes on/stays on/goes off/stays off. I think it's probably a short somewhere.

hey i think i have one of those too in my 89 trooper but its just the lil light, mine is on sometimes too, i will take a pic tonight

that is in fact an aftermarket anti theft device. ties into the start circuit and is VERY easy to bypass/remove. i cant say for sure without seeing the connections but every time ive looked at an install youll see a bunch of black or white wires coming from the device and 2 of them are slightly larger than the rest. those are the 2 that tie into the starting ckt.

anyone with a basic understanding of automotive electronics could remove it. (as long as it wasnt installed by isuzu engineers. knowing them itll be tied into something stupid like the left turn signal. <img src="/forums/images/graemlins/lol.gif" alt="" /> )