We just started having this issue too with our 2000. We thought it was the low-fuel chime, but it has enough gas. There doesn't seem to be any consistency - did you find out what it was on your jeep?
I own a 2000 Jeep Grand Cherokee Laredo, V6, 4WD. Driving along I will here the 3 warning beeps but no other info, usually I see low windshield washer fluid or a low coolant warning message. Anybody else having this problem?

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