[RockHQ]

The only thing electronically controlled in a 700R4 is the torque converter lock-up clutch. The lock-up solenoid gets it's signal from the VSS, or vehicle speed sensor through the ECM.
A Finnish guy made an add-in controller that greatly improves how the TCC engages and the vehicle speed needed to engage it. It requires basic electronics knowledge to build it, but it doesn't use any exotic components at all. I can post the schematics he made here if anyone's interested. I haven't had the time to build my own one yet, but since the cost is negligible i'll do it time permitting.

-Axle