Hi HammerStriker
I had the same question so I took a screw driver and unmount the overhead console of my carnival(sedona) that does not have the trip computer feature to compare with one with the trip computer.
I found that a wire bus was missing in my car, probably probably the one that brings all the car sensors information to the computer. In other words, you cannot just replace your overhead console with one equiped of the trip computer.
If you look to the 2 console pictures you'll see that the one with the trip computer requires 3 wire bus whereas the non equiped just has 2.
Of course you can consider adding the missing wire bus but this will require much more effort and it will probably cost a lot.
Guifoun
ImageShack - Hosting :: tripbackbv2.jpg
ImageShack - Hosting :: notripbackmz6.jpg