The ABS light on your 2001 Jeep Cherokee will come on when the ABS control module detects a fault with the ABS system. You are experiencing and intermittent fault - the light will be on only when the fault is present. Diagnostic fault code(s) should be stored in the ABS control module which will be of help in diagnosing your concern. A scan tool or quality code reader will be necessary to access the fault code(s). The ABS is disabled whenever the ABS light is on and should function normally when the light is off. Please use the following link to find a shop near you for help diagnosing your ABS issue - http://repairpal.com/directory?address=77086&car_brand_names=Jeep.