2004 Grand Vitara, 2.5 V6.  Canadian Spec (should be same as US?).

The 4sp Auto is set to kick down way way too often.   I would rather it didn't kick down except in extreme circumstances.

I would like to find my TCM so that I can try a plan I have.  Where is my TCM located? Bonus if you can tell me colour codes at the plug.

My plan is to run a rheostat in the sensor feed coming from the throttle position sensor to the TCM, so it thinks it's at 40-50% throttle when it's at 75-80% throttle, so as to eliminate a number of kick down actions. This would be done by running that signal to ground via a resistor.
 If that works great, if not then I'll run a junkyard TPS, run 12V to it and let it send out a fixed 40% TPS signal.

My one concern is the transmission lowers internal (band) pressures drop at lower throttle positions, like some of the old mechanical systems did for a softer shift feel.  If so, then I may end up with more torque at a lower internal pressure, causing slippage.