# Shiftyness **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [June 4, 2009, 3:03am UTC](https://community.cartalk.com/t/shiftyness/31405 "2009-06-04T03:03:27Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/cartalk/original/3X/1/d/1d47c66a543aa6c5a7873bb2320858f978ff52ed.png) [@system](https://community.cartalk.com/u/system)\ **Post date:** [June 4, 2009, 3:03am UTC](https://community.cartalk.com/t/shiftyness/31405/1 "2009-06-04T03:03:27Z")
441 miles, and 11 1/2 hours ago, I left Concord, went to Richmond to pick up the cargo, stopped off in Fairfield and picked up blood and delivered that to Woodland and then proceeded to Reno to deliver the Richmond load. Bay Area to Reno, where I gassed up, 19.3 MPG. Goody. Now to shifting. I know, It’s a Tundra, but the Dakota did it too, and I bet so does every other automatic, and I am curious as to why this happens; The transmission shifts back and forth, going up hill, while on cruise. Take it off cruise and hold exactly the same speed and it doesn’t shift out of the same high gear it will not hold in cruise. Howcome? ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [June 4, 2009, 3:14am UTC](https://community.cartalk.com/t/shiftyness/31405/2 "2009-06-04T03:14:22Z")
No, not EXACTLY the same speed…As the CC senses the speed dropping off it opens the throttle not caring about a possible downshift linked to throttle position. You on the other hand KNOW when a downshift is imminent and subconsciously avoid it, preferring to accept a SLIGHT speed loss. The CC will accept NO speed loss… ---
**Author:** ![system](https://global.discourse-cdn.com/cartalk/original/3X/1/d/1d47c66a543aa6c5a7873bb2320858f978ff52ed.png) [@system](https://community.cartalk.com/u/system)\ **Post date:** [June 4, 2009, 5:20am UTC](https://community.cartalk.com/t/shiftyness/31405/3 "2009-06-04T05:20:48Z")
True. So you are saying it is just really, really sensitive? ---
**Author:** ![chunky\_azian](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@chunky\_azian](https://community.cartalk.com/u/chunky_azian)\ **Post date:** [June 4, 2009, 7:43am UTC](https://community.cartalk.com/t/shiftyness/31405/4 "2009-06-04T07:43:56Z")
When you’re on cruise, it doesn’t know there’s a hill until speed drops. Then it tries to get back to the ordered speed by opening up the throttle, so much so that the transmission decides to downshift. Once it gets to the commanded speed, cruise, which doesn’t know whether or not you’re still on a hill, backs off on the gas and speed drops. This process repeats. When you take it out of cruise hold the same speed, you know there’s a hill. Unlike cruise control, you don’t back off once you reach your desired speed. Your speed doesn’t drop so you don’t need the lower gear to get back up to speed. A good automatic computer would know from acceleration rate and throttle opening that you’re on a hill and hold a lower gear for the climb. ---
**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\ **Post date:** [June 4, 2009, 11:11am UTC](https://community.cartalk.com/t/shiftyness/31405/5 "2009-06-04T11:11:45Z")
Cruise control is reactive, not proactive. You know when you’re going up a hill, and you step on the throttle a bit in anticipation. The cruise control only reacts when the vehicle loses speed. If you waited until the speed started to drop, and then stepped on the gas to increase speed, the transmission would downshift. It’s all a function of how far the throttle opens. And, yes, all automatics do this. ---
**Author:** ![circuitsmith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/circuitsmith/32/40376_2.png) [@circuitsmith](https://community.cartalk.com/u/circuitsmith)\ **Post date:** [June 4, 2009, 7:53pm UTC](https://community.cartalk.com/t/shiftyness/31405/6 "2009-06-04T19:53:20Z")
The cruise control and transmission would need to “talk” to each other, plus an inclinometer to detect hills, to do as well as a skilled driver.