Indicator Lights 4710

[Coloradokid]

I have an older JD4710. After changing the battery recently, the indicator light flashs one short, two longs, one short. Tractor seems to run OK. Any ideas what that code is telling me?

 

[Zebrafive]

MFWD sensor

 

[Coloradokid]

MFWD sensor

Thanks. Where do I find info on how to check it out? Operators manual not much help.