The BD AutoLoc is a computer that commands the torque convertor lock-up clutch to stay applied when an exhaust brake is engaged. The AutoLoc ensures that 100% of the retarding force is being transferred in 3rd and 4th gears, thus, transmission oil temperatures remain low because convertor slippage no longer occurs in these gears. The lock-up clutch and brake automatically disengage at low speeds to prevent stalling and transmission and convertor damage. The convertor lock up clutch applies with accelerator pedal pressure, and the AutoLoc captures this signal. After shifting out or into overdrive in Dodge trucks, apply heavy accelerator pedal pressure or quickly release the pedal and the lock up clutch will engage. Exhaust brakes cause high automatic fluid temperatures due to the torque converter slippage and without a AutoLoc only 10-80% of the retarding force is transferred through the (unlocked) fluid coupling of a torque convertor. You can drive the truck with the AutoLoc engaged all the time. If you experience a shutter when you slow down in over drive with the AutoLoc engaged, you need to have the AutoLoc reset to disengage at a higher vehicle speed. However, variances occur due to rear ratios and tire sizes.