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Discussion Starter #1
Eric, My truck (01 duramax) as what seems to be a lazy cruise control. On level ground it holds the truck within 2mph of set speed but on rolling hills it will very as much as 10mph on either side of the set speed. I have complained to the dealer several times and they said it is within specs. I have three other older chevy trucks a the cruise works great on them. What gives?


Thanks


Robert
 

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I have never driven a 6 speed truck so I cant attest first hand. I wouldnt think it should vary by that much. Any body else have a hand shaker that can chime in?


Eric
 

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dmaxalliTech said:
I have never driven a 6 speed truck so I cant attest first hand.

Neither have I! And we sell and work on a bunch of DMaxes! Not many people choose the 6 speed over the Allison.
 

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craneman,


I have a 6 speed and the cruise stays within a mile or two always. Even here in the mountains where I live. Going down a steep hill and then climbing back up is where it varies the most. Seems like as the truck starts to coast a little fast then has to make up its mind when to hit the gas to go up the next hill there is a little over fueling pushing it a little fast. Here in Montana the cruise is always on 75 even in the parking lots
Don't let them tell you it is normal. This whole drive by wire is pretty darn acurate. Best of luck,


Steve
 

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Mine works just like Steve's, perfect description. I've never seen it get anywhere near 10mph off maybe 3 at the most, and just the way he says.
 

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Discussion Starter #6
Thanks for the reply. The service manager told me that the ZF had the same cruise program as the Allison and that was why the cruise acts that way. I though it should work better then is does.


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Robert
 

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sounds as if you better have the dealer reevalute their prognosis. I think you have a problem, hard to say for sure what it could be with out looking at it first hand


Eric
 

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Sorry for the late reply, not too many hills here, but otherwise my cruise captures the speed and holds it pretty much dead on.
 

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I know exactly what you're talking about craneman. Unloaded it isn't bad, but with the 5th wheel behind on rolling terrain it's just stupid. I can hold it within 1 mph with my foot, but the cruise is swinging +10 to -10. Say it's 2 MPH over the set spped and coasting at the bottom of a hill, starts up the next hill but doesn't even fire up the engine until it's down by 5 MPH, SSSSLLLLLOOOOOOWWWWWLLLLYYYYY rolls on ALL the power and shoots back through the set speed while still climbing the hill, goes over the crest at the set speed +5 and still accelerating, finally backs off completely at +10 MPH on the downgrade, coast back down to about +2 MPH. . .sound familiar? This doesn't happen on interstates, (I-70 west of Denver and Interstates 25, 80, 15 and 90 going to Missoula) where the vertical "curves" are more gentle, but on US 34 between Kersey and Wiggins in northeastern Colorado it'll make you






The cruise control seems to have enough authorithy to command full power, but it takes something like ten seconds to go from 0% to 100%. I guess they wanted it to feel smooth.






It's a trivial complaint in a truck that I love, but I do wish the cruise acted more aggresively, like every other GM cruise control.
 

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I tow a 9000 lb. 26 foot tounge trailer and mine's pretty darned accurate. Sometimes it falls off a little at the start of a grade but never more than 5mph. Then when it catches up it pulls it back and holds it just fine. When mine gets confused is when I start helping it. Then I have to let my foot out of it and it takes a second for it to realize to get back on the gas.
 
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