In reading several threads on the manual TC lockup switches for OBS trucks, I've come across some conflicting info. Specifically, will the manual switch force lockup in 2nd gear when the gear selector lever is in 2 (as opposed to drive) The functionality I'm looking for is to be able to force lockup in second gear when towing heavy up steep grades, as that is the only time I get anywhere close to trouble with tranny temps. (225ish is the highest I've seen, which I don't like.) Many thanks!

 

With the switch it will lock the converter in any position except when the gear selector lever is in R or 1. It will lock in P, N, OD, or 2.

 

Thanks Mark,

That was what I was hoping to hear.