Warning light and buzzer. Probably low on fluid Dextron III. Now...why is it low?
In my case, two of the hydraulic hoses failed in about a month.
First was a 7 footer...to the front jack on the drivers' side. Then, later, a 30 footer to one of the rear jacks (passenger side). Both had pinholes...due, I think to rubbing and age.
Also...check out the jack(s) "foot". If there is oil there, the seals in the jack went bad.And that is where the leak is. Then the fun starts. Either in the owners manual or (better) the website, you get a listing of all their jacks. And the "replacement" models for the older ones.
Some are rebuildable...others are not. Of course mine (2001) fall under the "NOT rebuildable" category. Of course. Checking the internet for used ones, I found ALL of the ones listed kinda shaky or actually incomplete. 1/2 price, of course. used. (Will they work? DO they work? Who knows?)
NEW ONE: They won't sell it to me...only thru a dealer or retailer. BS. So i had to go to an RV dealer and have them order it for me. Must have added 100 bucks simply to make the phone call. A bit over $600....just for the replacement jack (which, by the way is "rebuildable") and I did all the work of removing the old and installing the new.
Job is simple, but you need good tools. A GOOD 200psi compressor and a GOOD Snap-On impact gun. The handy-dandy Harbor Freight items just arn't up to the job. Get the new bolts, nuts and lock-washers from Grainger Tools. Good hardend hardware. I think my 5/16-18 bolts were 1- 1/4 inches long. Bad thing about Grainger...you must by 100 of each. About 100 bucks. But no-one else has these hardened fasteners. So...you have extras for when the rest of the jacks fail. (humor).
G'luck!