6 speed transmission questions.
So I came out of the ice age and got a Suburban with the new 6 speed transmission (PRNDM_1). Reading the manual, it seems a little daunting. So how do you use it when towing? And what about steep...
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That's when using cruise control, grade braking is when using the brakes. De-activate cruise and the vehicle momentarily upshifts and freewheels, until it figures out that you need engine braking. That's not unique to GM, they all screw up the transition I believe the functionality is similar to the 2013's, mine was a 2011 and acted much the same. Except the hill start feature....
GM -
"Tow/Haul mode, activated by a button on the shift lever, modifies the standard six-speed transmission’s shift mapping to take full advantage of the Sierra’s powerful new EcoTec3 engines. Under acceleration, shift points are higher for more power, while downshifts are initiated earlier to promote engine braking, reducing wear on the Sierra’s disc brakes.
With Tow/Haul mode engaged, Sierra’s Trailer Grade Braking is activated when the driver lightly applies the brakes. This feature initiates downshifts to assist with braking on long downgrades. In addition to slowing the vehicle more efficiently, Auto Grade Braking can reduce brake rotor temperatures by 100 degrees Celsius during a braking event.
For drivers who prefer full control over their truck’s shifting, improved TapShift controls on the shift lever are backed by a patent-pending shift algorithm that improves shift response time by up to 60 percent compared to previous systems. When the TapShift controls are in use, Sierra’s Trailer Grade Braking is deactivated because the driver is manually controlling gearshifts."
http://www.gm.com/article.content_pages_news_us_en_2013_may_0531-gmc-sierra-trailering.html
GM -
"Tow/Haul mode, activated by a button on the shift lever, modifies the standard six-speed transmission’s shift mapping to take full advantage of the Sierra’s powerful new EcoTec3 engines. Under acceleration, shift points are higher for more power, while downshifts are initiated earlier to promote engine braking, reducing wear on the Sierra’s disc brakes.
With Tow/Haul mode engaged, Sierra’s Trailer Grade Braking is activated when the driver lightly applies the brakes. This feature initiates downshifts to assist with braking on long downgrades. In addition to slowing the vehicle more efficiently, Auto Grade Braking can reduce brake rotor temperatures by 100 degrees Celsius during a braking event.
For drivers who prefer full control over their truck’s shifting, improved TapShift controls on the shift lever are backed by a patent-pending shift algorithm that improves shift response time by up to 60 percent compared to previous systems. When the TapShift controls are in use, Sierra’s Trailer Grade Braking is deactivated because the driver is manually controlling gearshifts."
http://www.gm.com/article.content_pages_news_us_en_2013_may_0531-gmc-sierra-trailering.html
