Inspect reverse switch

Inspect reverse switch located usually on upper side of transmission, possible access from manual shift boot. Most likely switch is a normally open switch unless air is applied (this case switch will close when reverse is engaged) unfortunately, we do not have access to wiring for your truck We did ask a few mechanics for you. all of them mentioned reverse switch below are some links, pictures and manuals, hope it can help you. We will continue in trying to find more information regarding you issue. Please come back and state in the comments how you solved the problem. We will keep the records for future truckers with same issue Check below links Do not purchase below, We are trying to help you visualize the switch https://www.mylittlesalesman.com/zf-transmission-for-a-2006-freightliner-columbia-120-12320657 https://globaltransmissionsupply.com/zf-freedomline-transmission-operator-manual-tp-20170.pdf https://www.ebay.com/itm/186187495757?epid=1262867769&itmmeta=01HTV2AGAKVBAVXB55ZPGQ80E5&hash=item2b59a3b94d:g:aXIAAOSwxHZlZ6En&itmprp=enc%3AAQAJAAAA4P%2FUSEFe%2Fmxu8IVSjVtr5%2BUHDr26%2Bv3HdHhRl1GrIqkT6Lxq98efVrq4wwC0KmJU5YTEF7MTXtC1QtEq5Y753BZKGksLVxpq6JnuEbV%2BnlqMHFKKmL3lnECnwIfWlfaP4fNGaVT5M3OgiEbIEj4OCw4UcS3dEdLIeyrZpezJEdLkT3CvOyd1AQHrCGIq3SjsNdnF0Bu6YztYtJeuaAi2dfjj4RbkxknzLeW40LoLo50GShLCjSh6hnzqWso4XvQM%2FjLwOBg96H7%2FKjJCpzKp5Wb9TFZxvB8D8vR%2FyxcO6L%2Bp%7Ctkp%3ABk9SR7CFquLWYw https://www.truckid.com/fuller/reverse-switch-mpn-4302748.html?singleid=2630528457&url=3373549&vehicle=9451 https://globaltransmissionsupply.com/zf-freedomline-transmission-operator-manual-tp-20170.pdf