[Bpokey]

There is a pressure switch on the valve body that will only let the converter lock up in 4th gear. There were 2 different switches if I remember correctly, one that is normally open until pressure closes it in 4th gear and the other is normally closed until pressure opens it in 4th gear. Sounds like your switch is the opposite of how the diagram shows how the wiring should be and it is locking the converter in all gears but 4th. I think you have a switch that is closed until 4th. I had the same issue with my 2004r and ended up wiring it with a relay that would close when it was ungrounded from the switch in the valve body and complete the circuit to the converter. Hope this helps.