Dylan JZ;1644968 said:mine had ABS with the 7M, but it's never been active with the 1J.. the light always comes on right after starting the car (shrug), I wish it worked. It's likely a wiring problem I suppose, but I've also heard that some 1Js won't work with ABS for some reason or another, I can't remember what the actual argument was. Aaron from DM comes to mind in relation to that topic IIRC.
If you use the 1J 5SP and it doesn't have the rear speed sensor will make the light go on and the abs not to work. For some reason my 1jz & tranny came with the speed sensor. 1.5jz now but i have working ABS.... Althought i'm running into braking issues now =/
As stated before, relocate the battery if you really need the space. Less work to do as well.