Kary (Big Blue) sent me a PM, reminding me that the OD solenoid valve circuit, the one that actually powers the valve and enables o/d, on a/t trucks, runs thru the cruise computer. This enables a 4-3 downshift in cruise without having to move the tv cable far enough to make that happen by a very large thtrottle movement. If the truck is at freeway cruise, holding speed on an upgrade ofthen forces a downshift. If the set speed exceeds the actual speed for some set amount of time, the cruise unit triggers the downshift to keep from lugging the motor.

Not responsible for advice not taken...