Cadillac Repair: 95 DEVILLE CONCORSE, concorse, accellerator

Question
THE CAR SEEMS TO SHIFT FINE TO 25 MPH IF YOU TRY TO ACCELLERATE THE SLIGHEST, IT WILL DROP INTO A LOWER GEAR. I CANT TELL IF IT IS FIRST OSECOND, SINCE IT SHIFTS SMOOTH ON TAKE OFF. I CAN ONLY ASSUME IT GOES FROM IST TO SECOND AND BACK TO FIRST. I CAN GET THE CAR TO 25 ON LEVEL GROUND AND IT WILL SEEM TO DRIVE FINE, UNTIL I SLIGHTLY TOUCH THE ACCELLERATOR, THEN IT WILL DOWNSHIFT AND THE ENGINE WILL RACE. THE FUSE FOR THE TRANS IS OKAY. SOMEONE ELSE SUGGESTED A SENSOR. WHAT SENSOR AND WHERE WOULD IT BE LOCATED.------------------------------
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-----Question-----
I JUST BOUGHT THIS CAR AND IT DROVE HOME FINE. THE NEXT MORNING ON THE WAY TO WORK, I WAS DRIVING ABOUT 50 MPH AND THE CAR SUDDENLY DOWNSHIFTED AND MY SPEED DROPPED TO 25. I GOT TO WORK AND IT SAT FOR 5 HOURS BEFORE I TRIED TO SEE WHAT WAS WRONG. THE BATTERY WAS DEAD. MY BOSS CHECKED THE BATTERY FOR A LOAD TEST AND SAID IT WAS NO GOOD. PUT A NEW BATTERY IN AND DROVE OUT OF THE PARKING LOT AND IT WONT SHIFT INTO HIGH RANGE. FLUID IS FULL. WHAT COULD HAVE HAPPENED?
-----Answer-----
Define HIGH RANGE.

Does it shift from 1st to 2nd ?.

2nd to 3rd ?.
3rd to 4th ?
4th to overdrive ?.

Answer
It could be a fault inthe "B" shift solenoid located on the valve body of the trans or a pinched "B" solenoid wire at the valve body.

You need to have the trans pressure tested in order to diagnose the fault.

The "B" solenoid requires removal of the trans.