Sounds like you may have used up the three unlocks. You can only unlock it three times after that you need to send it back to SCT to have it reset.
The only reason to unlock it is if you want use it on a different truck or you have had a reflash.
A forum community dedicated to Diesel engine owners and enthusiasts. Come join the discussion about performance, builds, ecodiesel, towing capacity, modifications, classifieds, troubleshooting, maintenance, and more!