I have a 2004 a300 that the 2 speed is not working. I can turn on speed management and use the joy stick to change the drive percentage. Checked all the wires and fuses all seem good. Would like to know what valve does what on the 2 speed valve and what wires control it coming out the joy stick?
Did you ever resolve this? I have the same issue, code 38-16. Faults to lowest speed. Was told I needed a new controller. Found one but that hasn't solved the issue. I'm guessing you have the round base joysticks?
Wondering if it could be the main controller. I believe they communicate together. Haven't found any frayed or gnawed wires.