need help

Hi,

I have a 99 grand cherokee laredo with select gear, I6 engine, 4X4

recently, my jeep got a really weird problem. When I was driving, the headlight ws some times normal, sometimes dim.then the abs light on dishboard is on. After I turned off the engine, the power is vanished. 15 minutes later, everything is back to normal. my car has this kind of symptom for two times recently.i checked battery, it is fine. I think that the problem is coming from laternator, or abs relay or censor. any idea?

thanks a lot.