[Desert185]

Originally Posted by JRTJH

I can't speak to how the GM or RAM systems work, but the Ford exhaust brake operates in conjunction with the cruise control and the transmission (either in tow/haul or regular) operation. When in normal operation with the exhaust brake activated, as the transmission downshifts, a "slight" braking will occur. in tow/haul a more aggressive downshift happens, and the exhaust brake action is also more aggressive, probably because of the increased engine RPM from the downshift. Tapping the brake pedal will cause the transmission to downshift, increasing exhaust braking action at the same time. Additional "brake pedal taps" will cause continued downshifting (one gear with each tap) until the vehicle is in 1st gear (higher vehicle speeds will delay the downshift until the transmission can downshift without "overspeeding" the engine). ie: The truck won't downshift into 1st gear at 70 MPH.

With the cruise control set, when descending a hill, the cruise will detect any speed increase and downshift the transmission to compensate and slow the vehicle, with the exhaust brake activated, there is a marked increase in braking action. I have not "heard" the exhaust brake, but do notice the engine sounds at higher RPM. There is no "jake brake noise" with the Ford system.

I can "visualize" how, on an icy or wet, slick road, tapping the brake pedal , even if it's just to deactivate the cruise control, and the "automatic downshift" that occurs causing the vehicle rear wheels to "lock up" causing loss of control. The exhaust brake can be deactivated by simply pushing the dash button, but once a slide has started, with the transmission in a lower gear causing deceleration, I don't know if pushing the button would do anything to help regain control of the slide.

With the ice and snow covered roads in northern Michigan, I'm not inclined to want to do much experimentation in traffic with the system. I'll probably do some "lonely back road" type trials this winter, but my current plans are to not even consider using tow/haul or exhaust brake systems on icy roadways.

I'm with you on that last sentence. Meanwhile, I'll continue to use what appears to be a more user friendly PacBrake and six-speed manual transmission combo, whether slick roads or not.