What does the OD overdrive off do on the 2007 trucks with the 48RE? Yeah, duh, I know it disables overdrive (4th gear) but it also seems to affect when the TC locks up. I was thinking it would be just like tow/haul with the increased line pressure but would not shift into 4th but it definitely is not locking the torque converter like tow/haul does. Why would I not want overdrive off to act just like tow/haul only without the top gear? Anyway I guess that is more of a question for the dodge engineers....

 

You get OD off or TH, not both. ECU is not smart enough or big enough to do TH in 2 places.

 

If you read the owners manual it has a poor explanation of when OD off would be useful. I know the gasser rigs have the same thing.

 

So...

Under light throttle, when in "normal" transmission mode my TC locks in at around 50 mph/2000 rpm/ 4th gear (stock tires on 48re - 3.73 rear).

Under light throttle with tow/haul, locks in in 3rd gear...

With OD off, under lighty throttle, when does my TC lock up?? I hope it still locks in third gear or the trans might overheat if towing heavy and avoiding gear hunting between 3rd and 4th by using the OD off feature

 

I've been wondering the same thing too. It feels like it never locks in OD off mode in my truck. But then again I don't think I want it to lock cause I want it to go out so Dodge has to replace it under warranty. Don't listen to me though, cause I can't stand my tranny right now. Anyways, I want to know the same thing you do. Does it lock up in 3rd with OD off?