I drove through Salt River Canyon in Arizona last month towing a 13000 pound 5th wheel. This was the first time I had really used the exhaust brake. It is a 9 mile 7% down grade with switch backs. The first few times I had to use the brakes to slow down I noticed that the transmission would down shift as it started to re-gain speed. I thought, why step on the brakes, just use the manual switch to down shift. So I did this and it would slow me down. If I got too slow, I would shift back up a gear. I toggled between 3rd and 4th gear all the way down the hill and maintained a safe speed between 30 and 50 mph. Only once I shifted to 2nd to slow to about 20 on one of the switch backs. This seemed to me like a better way than using the brakes. Has any one else done this?

 

Yes sir that is the intended purpose of the select shift. But to answer your question...yes your exhaust break was working while in combination with your downshifting...it also would have been working if the truck was in tow haul in automatic shifting mode.