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Discussion Starter · #1 ·
I have two (03 Ram 1500 and 04 Grand Cherokee) that appear to be doing the same thing. While driving with cruise control on, the transmission appears to fall in and out of top gear. Neither does this with cruise off. Any ideas on where I need to start troubleshooting? Both are 4.7 with 545RFE. Ram has 280k miles, GC has 89k with a fresh Powertrain Products rebuilt transmission.
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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Both have electronically controlled shifting with interactive speedcontrol. It will downshift abruptly to hold set speed, sometimes it is an annoyance if there is no traffic around.
There is no real adjustment for this. It is all in the software.
Some PCM software upggrades will address the abruptness.
It is worse with hilly country and loaded vehicles. In cases like this, I turn off the speed control and drive with my foot.
tsb_wj_1801304.pdf (wjjeeps.com)
 
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Discussion Starter · #3 ·
Both have electronically controlled shifting with interactive speedcontrol. It will downshift abruptly to hold set speed, sometimes it is an annoyance if there is no traffic around.
There is no real adjustment for this. It is all in the software.
Some PCM software upggrades will address the abruptness.
It is worse with hilly country and loaded vehicles. In cases like this, I turn off the speed control and drive with my foot.
tsb_wj_1801304.pdf (wjjeeps.com)
Thanks for the response, but I don't think this is addressing the symptoms I'm experiencing. The fix may certainly be the same. Predominantly on flat highway I get a ~200 rpm increase and it feels like the transmission is not quite engaged. It continues that way for a varying amount of time and then returns to normal. As I said above, this doesn't occur when not using cruise. Again, thanks!
 

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My parents have a 2001 Dakota 4.7 with this same Trans and it started doing something very similar to this about 10 yrs ago. It was the solenoid pack which is above the valve body in the transmission. The 4.7 does do some hunting on the highway even in a lighter Dakota but this one was different in that it was constantly doing it even on level roads. It would move a few hundred rpm just like you are experiencing. Maybe something to look into with yours. They still have the truck and it hasn't done that since the replacement of the solenoid pack.
 

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Thanks for the response, but I don't think this is addressing the symptoms I'm experiencing. The fix may certainly be the same. Predominantly on flat highway I get a ~200 rpm increase and it feels like the transmission is not quite engaged. It continues that way for a varying amount of time and then returns to normal. As I said above, this doesn't occur when not using cruise. Again, thanks!
This is normal. It will downshift to hold the set speed when coasting on a slight downgrade, or on a slight upgrade. But I have found if you have Autostick, you can put it in the manual mode, and it will not do this.
 

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My ZF 8 speed shifts 2 to 3 times more often on cruise control compared to manual. You will find that you allow speed to drift some in manual but cruise will not allow that drift. Also you may notice if you watch your habits you will find you slightly increase the throttle before you hit a hill. Cruise only knows after you are on the hill.
 

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Cruise control is much more aggresive with the throttle in order to keep the speed firmly set, hence the tranny will shift more.
 
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