Transmission Slipping
 

2003 TL with 227,000 transmission started slipping all of a sudden. When cold, shifts good; when warmed up, slips before going in to every gear. Once engaged runs fine. I checked the A and B solenoids on the top of the tranny individually. When 12V is applied they click and the valve slides without any hesitation. The check engine light came on and the D5 indicator blinked until I recycled the key. There were a couple of codes stored that indicated the transmission position sensor and the A & B solenoids could be the cuprits. Like I said it seems that the solenoid test passed. Do you think the position sensor would cause this? My wife took it to a shop and they said it is a internal malfunction. Why does it work fine cold then? The codes have been cleared and I have't driven it far, but it does act up when it gets wamed up! Looking for input! Thanks!!!