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Johnny T
Dodge Dakota
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5/09/2005
22:39:22
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 Subject: Down shifting tranny
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I have a Dodge Dakota Quad cab, 4.7 engine, auto transmission. I absolutely hate the fact that when using the cruise conrol, that the transmission down shifts when going down hill. I live in hilly country so this is a real pain. Question, is it possible to reprogram the tranny not to do this?
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Kotagious
Dodge Dakota
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5/09/2005
23:51:28
| RE: Down shifting tranny
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I have the same truck and it does the same thing, but I think it comes in handy, especially when towing a heavy trailer. Sorta works like an engine brake. If you notice, it doesnt just do it when in cruise control but whenever you go downhill and hold the acelerator at a steady level. But when you in cruise control, it keeps the vehicle from getting over 5 mph from what the cruise is set on.
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JimmyD
Dodge Dakota
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5/10/2005
01:53:02
| RE: Down shifting tranny
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JohnnyT.
If you tell the Cruise Control system to maintain 50 mph, that's exactly what it'll try to do, whether you're climbing or descending a hill. Because it can't (thankfully) apply the brakes to keep the speed where you want it, the only thing it can do is to let off the gas, downshift, and use compression braking like Kontagious referred to.
It's perfectly normal operation.
If you have a 3.55 rear end, and your trip speed is 60MPH or less, try it twice with the Overdrive turned off: once with Cruise Control and once without. I think you'll be pleasantly surprised, and believe it or not, your gas mileage will increase slightly. I found mine gets better mileage in the 2600-3000rpm range (avg 16 mpg city/19+ highway) with O/D OFF under 60mph.
A quick look at torque/hp curves will tell you why.
http://www.wjjeeps.com/misc/curve_47.jpg
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Kowalski
GenIII
5/10/2005
15:45:59
| RE: Down shifting tranny
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That's funny; my '00 4.7 doesn't downshift like that. The cruise control won't keep feeding more fuel as you roll downhill, but the truck can continue to build speed due to gravity and doesn't downshift. I thought all were like mine; what you guys describe would require more complicated programming.
Lead, follow, or get out of the way
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Johnny T
Dodge Dakota
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5/11/2005
20:56:10
| RE: Down shifting tranny
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Message:
Thanks for the replies. But I just don't like it, I mainly travel secondary roads (No Troopers) back and fourth to work, 20 miles each way. The trans will shift about ten times each way. I guess It's just different from what I'm used to. I only pull a boat about once a month about 2500 lbs. The rear has 3.93 gears with posi trac. Gas milage is about 17.8mpg, interstate 19mpg. I love the truck only 14000 miles, I don't like the fact that it squeeks like 50 year old set of bed springs, guess they forgot to grease the body before it left the factory. But back to the original question, can you reprogram the trans not to downshift? Thanks JT
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JimmyD
Dodge Dakota
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5/14/2005
23:39:42
| RE: Down shifting tranny
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Kowalski,
Mine's an '04 4.7 with 545RFE auto trans, part time 4WD, and has the "New Generation Controller". That may be significant.
Tried it with wife's 2000 Grand Cherokee (same engine/trans, Quadra-trac full time 4WD), and it did not downshift with cruise engaged going down hill.
(shrug)
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Kowalski
GenIII
5/15/2005
16:05:02
| RE: Down shifting tranny
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Yeah, sounds like you guys have something different; mines the 45RFE with the seperate TCM. I'd rather have it the way you do, I mostly use it when there's cops around to keep me near the limit - have to watch it rolling down hills.
Lead, follow, or get out of the way
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