Using the exhaust brake on a steep descent requires an understanding of how it works, and the proper technique. The exhaust brake is most effective at RPM's over 2200, but if your speed and RPM's build up above 2500-2600 RPM, your transmission will automatically upshift, which reduces your rpms and greatly reduces the effectiveness of you exhaust brake. For downhill control, periodically apply your service brakes to keep the engine RPM's below 2500 so as to avoid an upshift. You want to use the service brakes enough to control the engine speed, but not so much as to overheat the brakes. On an extreme downhill slope of 7% or more, start down in 2nd gear and use your brakes intermittently in order to keep the transmission in 2nd gear. This requres descending at reduced speed (put your flashers on), but is much safer. If you allow the transmission to shift into 3rd or 4th gear, your braking and speed control will be greatly diminished.