To make the ODLO work, I believe you need to have the TCM and ECM programming updated (caution - going on memory here, could be wrong). Tell the dealership what you want to accomplish - they should be able to tell you what software is installed in your vehicle and what updates need to be made.
When you get your TCM and/or ECM updated, you will get the most recent update for your vehicle. So you would definetely get the ODLO feature plus any other changes they have implemented/fixed since then. I recently (February 2004) had both TCM/ECM updated and the truck works just fine.
The ODLO feature was added back in February of 2002 to the software controllers. If your vehicle was manufactured in March, 2002 or later, you probably have the changes. If your 2002 vehicle was manufactured before that time (like mine - 11/01) and if you have not had any updates, then you will need to get it done.
Forget about the light, take the vehicle up to 65 mph and hit the ODLO button. Does the thing downshift to 4th or continue in 5th?
Reference this technical document by GM (pg 6):
http://service.gm.com:8083/gmtechlink/arcv_pdf/7_02_e.pdfEdited by: OC_DMAX