Since your cruise only works in 4th gear, I suspect that it closely matches a factory rpm and speed combination. Albeit only in that gear. All other combinations are too far off for the cruise to turn on.
My only experience with this is how far off the shift lights were on a Metro that I used several different ratio transmissions in about 10 years ago.
This problem would drive me crazy since I drive 30 miles to work mostly highway. I would probably consider an aftermarket cruise control at this point as a possible solution.

 

It is. It’s like a 95% solid swap besides this.

i asked about a universal kit and can’t find one because it’s fly by wire.

 

I would contact Rostra, they make cruise controls for most rigs. I am pretty certain they can come up with components to use with your combo of GM parts. They work great on my drive by wire Fords.

 

Will do if I don’t get any headway with the bcm update.

 

Andy,
Would you expect in a situation like this to be getting incorrect gear ratio codes, or might it be that the other gears are close enough that it works without triggering codes?

Also, the statement was made that I believe the output shaft speed sensor was different between the two transmissions which is why the internals were swapped into your Vue casing.

TOTALLY NOT THOROUGHLY THOUGHT THROUGH TRAIN OF THOUGHT below.

Is it possible that the type of output shaft speed sensor is, for example, a hall effect based sensor (Vue) but the tone ring is set up so to speak for a reluctor based sensor? Might this be the source of the non-cooperation?

Especially since the input shaft sensor is going to also probably be set up the same way (Vue). So when trying to figure out what gear it's in, it's comparing two signals it doesn't understand. Maybe you could transfer the two sensors from the original transmission in the Cobalt if the reference voltage is the same and hope that the difference signal is proportionally the same as it would be in a standard VUE transmission. You may have to modify the wiring to give it a 5 volt reference or take one away.

Either that, or swap back in the input and output shafts from the Vue if that's even possible.

This is all contingent on determining how the input and output shaft speed is being sensed.

 

So I thought that maybe this company might have something that would help along with that but the guy said no.

https://sirhclabs.com/product/cortex...ensor-adapter/

its 100% a computer based issue not seeing the correct information in order to allow the cruise to work correctly, the question is- What exactly is the issue and is it feasible to fix. I don’t see myself pulling the trans again to put the cobalt case back in. This would cost lost of time and several thousands to have everything swapped back over. If it’s a lost cause I’ll find out what can be done to get a universal cruise in place.

i did get one e-mail back about the BCM and the guy told me this model is PCM based for the cruise and BCM.

 

Just for the heck of it

4th gear XFE trans

 

5th gear


5th gear XFE trans

 

Not the Cobalt case back in, swapping the input and output shafts from the Cobalt trans with those from the original vue transmission.

How many wires does the VUE output sensor have?
How many wires does the cobalt output speed sensor have?
You can say it's a computer issue but to me, this is a sensor mismatch issue. The computer is doing exactly what it's designed to do with the signal it receives. If you give it the wrong signal, to me that is not a computer issue. It's an input issue.

 

vue is 3 wire

cobalt is 2 wire

Speed sensors mount indifferent areas.

your saying swap the jack shaft?