In the picture (link below) there is a wire coming out of the transmission directly aft of the red box drawn on the picture, it looks like perhaps out of a plug of some sort. What is it's purpose? Thanks.

http://www.camaros.org/images/decode..._TH400_vin.jpg

 

OK, I did some research (which I should have done in the first place) and discovered it is for the electric kickdown on the transmission. It is attached to a swich mounted on the carburetor and actuated by the linkage. It provides for the kickdown function during hard acceleration.

 

On your TH400, that wire provides 12V to a solenoid valve inside the trans. That valve applies hydraulic pressure to one of the spool valves, causing the trans to downshift. On some cars (68-72 A-bodies, as an example) the switch is actually under the dash on the accelerator pedal.

Note also that on some TH400 transmissions there are two wires. The second wire serves one of two purposes. On the 65-67 transmissions with the switch-pitch torque converter, this wire operates a second solenoid valve that changes the angle of the stator vanes in the converter. On the 1970-up transmissions the second wire is a pressure switch that signals the transmission controlled spark solenoid to allow distributor vac advance in high gear.

 

Very good. Thanks so much.