I'm with Bob, I had a 2 gear and reverse ok problem it drove me nuts it was something electrical , poor connection or short the exact problem was never found after much work it just went away. If you have a electriconic problem you go 2 nd gear only as a default. You can work through your codes. There are a number of componets that are can be changed if you drop the pan. If you change them all out it will cost serveral hundred dollars. (been there done it). If you have a honest and good transmission sho they maybe able to help. A local sho the owner check mine and drove it twice and he told me it was the electronics. Good luck keep us posted maybe someone that know these trannies can help you more.