I think you should believe Harvey. He's the one with the STI badge.
On a more serious note the symptoms that match yours in the ATSG 4EAT manual, namely
"Car does not move in D or 3 range though engine revs up"
The only suggested "probable causes" they have listed are 53: "Faulty O.W.C. (1-2)" and 54: "Faulty O.W.C. (3-4)"
This would seem to tally with Harvey's suggested fix above, I'm assuming OWC means one-way clutch.
This problem is of interest to me, because my Black Betty has the symptoms "Car does not move in D,3 or 2 though engine revs up". In the case of my problem, though, after getting it rolling in 1 there was no way I could get it to engage 2,3 or D.
The suggested fixes were, in relevance order, Valve sticking, Bad TCU and 54:, Faulty OWC 3-4.
I changed the valve chest and the TCU with no joy. I also thought along the same lines as Trevor, thinking the speed sensor was faulty, although in our VTD type the gearbox has to come out to change it, unlike your US type.
In the end, I gave up and bought another gearbox. It's probably the OWC is what I have deduced in my case. And that's what it likely is in your case too.
Joe
