The GT Diesel 40420 will not tune a 2018-2021 Ram 6.7L until the bypass cable is in the harness. Install Bully Dog 42215 and leave it there. Bully Dog says that cable stays in place after installation.

• Build: This is a bypass cable kit for GT Diesel part 40420 only. It is not a tuner, and it is not removed after the flash.
• Part number: Bully Dog 42215. The GT Diesel page requires it on 2018-2021 Ram 2500, 3500, 4500, and 5500 trucks with the 6.7L Cummins. The cable page says 2018 and newer, currently 2018-2021.
• Fits: Those four Ram chassis with the 6.7L, 2018-2021, and only with tuner 40420.
• Does not fit: Not a 2013-2017 truck. Those need a different unlock cable. Trucks before 2013 do not need a special cable. Not a Power Stroke or a Duramax.
• Not in the box: No GT tuner. Order 40420 separately if you do not already have it.

Order today to secure your replacement. Confirm the truck is a 2018-2021 Ram 2500, 3500, 4500, or 5500 6.7L, and plan on leaving the cable installed.