What does P1715 means on a error code received from a 2001 ford escape?

My mom's 1998 Ford Explorer (4 door 4WD XLT with a V6) just had the "Check Engine" light come on (it's shifting/running REALLY rough) - and when I took it up to AutoZone (they'll hook their code scanner up to your car and figure out why the "Check Engine" light is on for free). They scanned it and got the same P1715 error code

• and their computer system said that this code means "Mechanical

or hydraulic failure of the shift solenoid"...and that the "Probable Cause" is either "low or dirty automatic transmission fluid". I went and checked her fluid level...and sure enough - it was just about 1 full quart low. So I topped it off...and it's now sitting outside with the negative battery cable disconnected (to clear the "Check Engine" code). I'll run it again in a bit and see how she fairs.

Second opinion:

Unfortunately, by the time a transmission problem shows up in the ECM, there is major damage. Be prepared to spend money on an overhaul.