[Alan Roehrich]

A stand alone TCU is a waste. There's no reason to need one or go through the hassle.The stock stuff works fine, there's several million dollars worth of R&D behind them for reliability. Adding some stand alone controller requires more wiring harness and adapting/interfacing that just adds complexity, and does not guarantee a solution.



It's more likely to be a wiring harness problem than an ECU. The wiring diagram for your truck can be found online, probably for free.



There are two ATSG manuals that are good for that transmission, one is a dedicated rebuild manual, the other is a manual that covers it and the 4L60E, and includes the electronic/electrical diagnosis.