4EAT does not engage 4th gear

[jetboy]

We have a new friend. His first act of SVXness was to get the car fully roadworthy again (I believe it had brake issues and had been standing for quite a few years). Since our Road Being (directly translated hehe) has made a slight error in registration, the VIN does not resolve well and details of the year or trans type is unknown.

What is known is that the car was sold with a transmission issue and that after changin fluids, this issue has persisted. He took the car to a specialist shop for autotransmissions but they could not connect to the TCU. He has tried the self diagnostics and no code is thrown. Since he's new to the car, I'm not 100% certain if he did a transmission diagnostics or engine diagnostics, we'll try to sort that out tomorrow. The specialists drove the car a lot and concluded that the car simply does not even try to engage forth gear.

He seems fairly intimate with cars and mechanics and since he hasn't said anything about sounds, I assume there are no sounds. 1-3 works just fine. I remember reading about something similar on the forum but a good 30 minutes of search did not reveal anything like this.

Any theories or pointers as to where he should go looking?