I have a 99 jeep grand Cherokee my abs light recently started to pop on and off and it feel like something is loose under my front in any suggestions on what might be the problem

 

The brakes I'd imagine. ABS sensor? Pads worn to metal? Have you taken the wheels off and looked at anything yet to rule out some possibilities? Hooked up a code reader? I don't know if ABS problems would show up on a reader but I know OBDII pretty much checks everything electrical.

 

The ABS has it's own module, like the Body Control Module. It can be read, but only with the diagnostics the dealer has. I have an intermittent ABS light on my 00 WJ, but they work even when the light is on. It's probably a wheel sensor that can't read the notched wheel on the hub. They get rusty and the sensor can't count the notches. Mine is weird because it'll pop on while I'm sitting idling in park. Turn the key off for about 2 minutes, restart and it's off. Weird.