2003 Overdrive Lockout

[DAVe3283]

Not sure if this belongs here or under Repower/Transplant, so please move if I guessed wrong.

My brother and I are finishing up a LB7 swap into his 2003 Suburban. The tow/haul button works, light comes on, transmission goes into tow/haul shift pattern. Holding it down for O/D Off does not work. Transmission remains in overdrive, O/D light doesn't come on in the cluster. It is like it isn't requesting O/D Off at all. But we can toggle tow/haul at will.

The wiring diagrams indicate the button on the shifter goes to the BCM, and that talks to the transmission. This leads me to believe the BCM may need reprogrammed. I have a Tech2 and TIS2000, but... what should I flash to it? A crew cab pickup OS? I don't want to lose any of the subruban stuff, like rear HVAC controls or MagRide.

 

[THEFERMANATOR]

The bcm controls the overdrive lockout. Any changes to the bcm could shut off suburban specific data messages and controls from the bcm. If it was mine, I would go with the 01 tcm os, then do the momentary toggle switch and led indicator for overdrive lockout. This way you keep all the suburban specific bcm functions, tow haul will work like stock, then you just have a switch and indicator light added to obtain the overdrive lockout. Otherwise I know Ben has figured out how to request over drive lockout in his stand alone setups, but I don't know if he's taking new orders right now or not.

 

[DAVe3283]

We did the Suncoast 6 speed conversion, which complicates matters, as Suncoast locks the TCM due to their custom OS. So unfortunately changing the OS is out of the question.

I may try putting the spare BCM in and flashing random stuff to it and see what all stops working. I'll shoot Ben a message as well. I wonder how Duraburb handles this? Or do most people do a LBZ swap, with the tapshifter?

Sent from my FlashScan V2

 

[THEFERMANATOR]

We did the Suncoast 6 speed conversion, which complicates matters, as Suncoast locks the TCM due to their custom OS. So unfortunately changing the OS is out of the question.

I may try putting the spare BCM in and flashing random stuff to it and see what all stops working. I'll shoot Ben a message as well. I wonder how Duraburb handles this? Or do most people do a LBZ swap, with the tapshifter?

Sent from my FlashScan V2

Last I heard, he's only doing LBZ+ for the last 5 years or so. I would call SUNCOAST, and see if they would swap you TCM's.

 

[DAVe3283]

Last I heard, he's only doing LBZ+ for the last 5 years or so. I would call SUNCOAST, and see if they would swap you TCM's.

I'll exhaust my other options first. Getting this TCM took over a month, so I'd have to be pretty desperate before I send it back to them.

Heck, if I have to sniff the Class2 message off my truck and make my own module, I can do that. Depends on how much my brother wants ODLO. I've been meaning to do some Class2 hacking for a while, so maybe this will be the excuse I need?

 

[BigBlock65]

Any progress on this? I have the same challenge with my 04 suburban / LLY / 5 speed.
I put the Fleece tapshifter kit in, but it skips 4th. It will downshift to 3,2,1 - but so will the column shifter... I really need 4th.

 

[DAVe3283]

The Suncoast 6-speed shift points are really good in conjunction with [THREAD=42711]my tune[/THREAD], as it turns out. My brother decided he didn't care to be able to lock out 5th. Then I ended up buying the Suburban from him, and came to the same conclusion, even when towing.

So my plans to make a box to do it got pushed to the back of the project list, and will probably remain there for most of this year. I am still planning on making the data bus sniffer for other projects, and if I learn the message(s) necessary to activate ODLO and the dash indicator light, I will post them up. But that is also scheduled for late this year the way things are going.

In your case, Ferm's suggestion of running the 2001 Allison OS with the external switch for ODLO should work. You could also reprogram the shift points so Tow/Haul locks out 5th, which might get you what you need.