1999 F355 F1 Transmission Failure Light - Stuck in 1st Gear

I think your thinking of the 360 Brian
Our cars engage the pump by the key only

You are correct about the obvious though when you say check to see if pump runs

All of us skipped right over that and assumed it was. Bad on us.

 

New pump is faulty.

 

... unless the original diagnosis was wrong. Was the original problem with the pump intermittent?

There is a relay between the TCU and the pump. Has this or other items been eliminated as possible causes?

 

Everyone keeps saying pump but do we all mean the pump motor because i have yet to hear-of a pump failure ever

I am thinking air in system but as others have said we are all guessing because we need way more info.

I cant help until we get more info guessing is a exercise in futility