Ok, so here's the story:

I'm traveling through the rockies towing a trailer and hauling a combined weight of approximately 6000 lbs. I have the tow/haul function engaged and the cruise control set to 55 mph. Going up hill isn't much of a problem. However, when going down hill I pass 55, then 60, when the transmission downshifts to 5th gear, the at 65 it downshifts again to 4th gear. But it doesn't bring me back to 55 mph. It finally stops accelerating at about 67 mph, so I hit the brake - which turns off the cruise control, but nothing else happens. Then I hit the brake again, but nothing happens with regard to downshifting or any indication that the engine brake is working.

I've read some of your posts saying that your engine brake keeps you at 45 mph and it seems that many of you are towing more than I am. But mine doesn't seem to be working the same.

So, what am I doing wrong?

Thanks for the help.

 

I'm not sure but I did not think cruise was part of the equation (being on). Someone will be along who knows................

 

I "think" that the engine braking and cruise control are mutually exclusive (not sure because I've never used the engine braking with cruise).

Here's what I do when engaging the engine break:

• Truck is in tow/haul mode.
• Let truck reach the desired speed going down hill.
• Tap the brake pedal firmly.
• Engine breaking starts immediately as truck gears down and revs climb.

The reason why I think that the engine braking does not work with cruise is because you engage the engine brake with the firm tap on the brake pedal. This disengages the cruise control.

Hope this helps.

Brian

 

This is exactly right. That is how I did it on mine towing a 9k trailer through West Virginia. Works very well. i set mine at 60 and it held there all the way down. Had to hit the service brake a time or two because of slower traffic.

 

The EB will work with the Cruise on. But if you tap the brakes to force a down shift, the cruise will drop off. If you use the minus button - on the stalk, The tranny downshifts and the cruise remains on.

For me, It is one of the advantages over my B&D Exhaust brake I had on my 2006 6.0L. Which ANYTIME the EB switch was turned on, The cruise was disabled.

The trick to getting the most from your EB is choosing the right speed. I have a road that I frequently tow my 13,000lb GN horse trailer up and down. It is 6-7 miles climb and the same down the opposite side. All at about 7-8% grade at 7000 foot summit. It's a 55 mph speed limit, with 40 mph caution signs on the curves and is heavily patroled.

I have found that if I set the cruise at 55 mph that it will creep up as you described to 60-65 mph, requiring me to force a down shift with either the brake pedal or the stalk button. 4th, 5h and 6th gear won't hold my load on that grade. but 3rd gear will, but 55 mph is too fast for 3rd.

So I have learned to slow to 48-50 mph at the summit, set the cruise and it will hold me for the down hill with out my having to use the brake pedal. Cruise will maintain the speed and force the tranny to downshift 6-5 then 5-4 and then 4-3, where the rpms will be up around 3000 rpm and it will hold my speed. The trick is getting the tranny into a gear where your RPMs are around 3000.

Now each load, Each grade, at any given elevation/air density will have a differnt speed/gear. And yes some grades/loads will run away and require the use of your brake pedal. But with a little trail/error I have found the speed/gears that work for my load at the elevations that I drive.