Rendezvous shifting problem

I have a 2005 Rendezvous with 7000 miles. For about 3 weeks now the "service vehicle soon" light has been coming on. This morning the dealer replaced the RADIO, which they said caused the problem, it didn't fix it so they ran another test and it indicated the new radio was bad, so they have ordered another one??? But, thats not my major concern. I also have a problem with the transmission shifting. If I get on the highway and accelerate up to 70 or 75 MPH the engine will turn 3100 RPM until I remove my foot from the pedal or release the cruise control ( adjust speed) then it will drop to the normal 2000 RPM. My question is: Is there any way this is normal? The service manager claims the shift point is at 70 to 75 MPH and I will need to adjust speed to allow it to shift.

I have a 2005 Rendezvous with 7000 miles. For about 3 weeks now the "service vehicle soon" light has been coming on. This morning the dealer replaced the RADIO, which they said caused the problem, it didn't fix it so they ran another test and it indicated the new radio was bad, so they have ordered another one??? But, thats not my major concern. I also have a problem with the transmission shifting. If I get on the highway and accelerate up to 70 or 75 MPH the engine will turn 3100 RPM until I remove my foot from the pedal or release the cruise control ( adjust speed) then it will drop to the normal 2000 RPM. My question is: Is there any way this is normal? The service manager claims the shift point is at 70 to 75 MPH and I will need to adjust speed to allow it to shift.

the shift points thing sounds about right< they are different from my other vehicles.

the shift points thing sounds about right< they are different from my other vehicles.

The difference is that I can drive 10,20,50 miles with cruise on and it will not shift unless I speed up or slow down. Then I can engage cruise and it will run at 2100 RPM. I can't believe this is the way it should be.

The difference is that I can drive 10,20,50 miles with cruise on and it will not shift unless I speed up or slow down. Then I can engage cruise and it will run at 2100 RPM. I can't believe this is the way it should be.

As I understand it, the level of torque it takes to maintain the 70 to 75mph speed may be such that the PCM may never decide to lock up the torque converter. However, if you slow down down just a bit or speed up a little and then let off the gas to get back to the original speed, then the torque level may be low enough that the PCM will command the torque converter to lock up, and it will stay locked up until the torque level gets high enough that the PCM decides to unlock it again. There is a bit of overlap built into these decision points so that the vehicle does not "hunt" excessively for the right transmission condition. Hopefully someone with more specific knowledge of your vehicle can comment on this, but I've noticed certain speeds in my own vehicle (2002 Saturn L) where the same thing happens. I've just gotten in the habit of "forcing" the lockup via throttle changes.