We are trying to wire up a th400 to a 71 skyl. custom. and on the engine wiring harness the wires are missing that are supposed to go to the tranny. and on the other side that passes through the firewall the 2 wires are there but we cant trace them because the harness is to big and full of other wires. So do all buick cars come wired for the th400 swap.? with the tranny presure switch also. ? which if they were all i would have to do is make the 2 wires in the engine wiring harness?
A 350 car would likely have come with a TH350 trans. Mechanical kickdown cable attached to the throttle pedal. One pink wire connected to the pass. side of the trans. activated the TCS on the carb., which allowed more vacuum advance in high gear. TH400 will require an electric kick down solenoid, controlled by a separate switch on the throttle pedal. Mike Garrison is reproducing the switch holders/brackets, possibly has a line on the switches as well. He is a member here. Another resource to check is George N.'s site where I think he discusses the swap. www.buickperformance.com
http://www.buickperformance.com/TH400GasPedalBrkt.htm The kickdown solenoid is in the pan. All you need is 12 volts on one side of the above switch(key on 12V from the fuse box), the other side of the switch goes to the vertical contact on the trans. That's it. The pressure switch (horizontal contact) is for pollution control. Don't wire it, you don't need it unless you are doing a concourse restoration
