Workhorse dash overdrive switch

[Dsrtrider]

I have a 2007 Voyage W24 workhorse 6 speed allison and on my trip this wknd the Overdrive switch on the dash stopped working, Does anybody have experience with this problem ? Where can i get a wiring diagram or diagnostics on that circuit? The O/D off lite comes on when I start eng and goes off so the Cluster should be working properly. There is power to the back of the Overdive swith just no action.

[Unplanned Tourist]

Will it go into either of the 2 overdrive gears?

I have the same chassis, so interested in what you find.

There are some wiring diagrams on the net, but hard to read.

Have you removed and replaced the plug on the transmission. It could be just corroded and needs cleaning and some dielectric grease.