2001 Chevy Express 2500 not shifting past 2nd gear

[versa7623]

Ok so just within a week 2 of our 4 work vans down for transmission problems great luck huh. So just to name a few problems with this van for about 6 months now I have been able to pull the key out of the ignition while running not sure if thats related to any electrical problems its been having as well. So last week on the way home it all the sudden started revving high before it shifted into 3rd then went back to 2nd and now it wont shift any higher than second, the reason im thinking its an electrical problem is the speedometer drops to zero during this and then comes back when I reach 35 mph and the battery light comes and goes constantly. Its thrown a few codes so I got them checked as well as the battery and alternator, replaced the battery and still does the same, they said the alternator is still good. The codes that came up were "Generator "F" terminal circuit fault", "2-3 shift solenoid valve performance", and "Fuel Injector circuit condition". Any Ideas? if somethings shorting what could it be? Thanks