I have installed the ODLO switch. When I get the TCM updated for the ODLO switch, will all current updates be applied to my TCM? Or, do I ask for just the ODLO update. Truck runs great and I don't want to change anything that might cause a problem.

As I found out you cannot just get one thing updated .... GM is like the government they have piggyback attachments .... With the OD/LO comes other upgrades also as with my 01...Something about cruise and OD holding IIRC ...


Your OD/LO may very well work ,have you tried it ??


Mac Edited by: Mackin

No, haven't driven the truck yet. The LED didn't come on so I assumed the lockout wasn't working. But what the heck, could be my wiring. Thanks for the suggestion. Will try it out tomorrow, before I make an appointment for a flash.

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

It was buit in 01/02. Was hoping the previous owner had the ODLO flashed. I'll give it a test drive tomorrow.


Good info. Thanks.

My light has never worked, but the OD lockout works perfectly. My build date was late May 02. I believe a software update occurred sometime between your build and mine, so it could or could not have the right software.

Had the TCM flashed today. ODLO now works as it should. LED still doesn't work. The LED has red and black leads. Figured red was positive. Maybe it's the other way. Think I reverse the leads and see?? Edited by: Lakedaisy