Started experiencing ACC / FCW Unavailable randomly that may have happened due to a little rough 4x4 on the beach last Fall. Also experienced "BRAKE" alert with alarm sounds while driving with no one in front me. Took my JGC in to the dealer in January as the issue became more frequent yet no diagnostic issue identified. After more research, including info from this thread, I took it in again, asking the techs to investigate more and this time I think they got it. This video accurately described the symptoms and was helpful to the tech:
(NOTE: I did not take this video - just googled it and it was exactly like my issue.) Here is the service write-up: CUSTOMER STATES ACC AND FCW RANDOMLY UNAVAILABLE AND CRASH ALERT INTERMITTANTLY. PERFORMED DIAGNOSTIC TEST. NO FAULTS STORED OR ACTIVE. ROAD TESTED SYSTEM - DID ACT UP. INSPECTED AND FOUND CENTER EYE BEZEL MISSING AND FACIA LOOSE FROM LIGHT IMPACT. REPLACED MISSING EYE BEZEL. SECURED FACIA. AIMED AND RECALIBRATED ACC/FCW SENSOR. ROAD TESTED BY SHOP FOREMAN A TOTAL OF 96 MILES. NO OTHER PROBLEMS AT THIS TIME. The price of the bezel was $30 and the labor was about $250. After several miles at highway speeds using ACC, it is now working and hoping it stays that way!