Driving home last night, I'm tooling along going 30-55mph, tap the trailer tow switch a few times, on... off... on... off... and for no, the OD lockout indicator comes on on my dash... its a D with a circle around it with a cross through it... alright, WTF? I have no OD lockout switch, never have... So I turn off TT mode, TT indicator dissapears, but OD lockout stays on... I punch the pedal, and the truck won't go up into 5th. After parking, shutting the truck off, and starting it back up, it went away and I couldn't get it to happen again...

:wtf1:

If you press in and hold the tow/haul, it will enable overdrive lock-out. Hope that helps.

short press switches tow/haul on off

long press locks out overdrive

Nice, I never knew that. I'd assume this is not the case on an '01 or '02?

Its in your owners manual, seems like a nice option to me.

No, 01s and 02s didn't have it , 03 was the first year. You can add the feature to the older trucks though.

whats involved in adding the feature to an '01?

Kennedy has the instructions on his site. www.kennedydiesel.com

Go to Tech Tips, then Duramax and it's in the list.

Mine has the switch. Well worth the little time and money to do.