The kickdown switch???

I've noticed that my car won't down shift when I floor it. I will just continue in third gear until I come to a stop and the car starts over in first again. The Centurion has a TH400, and as of what I've heard there is supposed to be an electronic switch that engages the down shift? On the driver's side of the gearbox there is a plug with two wires going in to it, one red and one black with a white stripe. I noticed that there was only one wire connected, and the other one was broken, just folded back, cause it had snapped right where the connection is. So I picked up a replacement from a yard and thought, well if I just put this on here we might have solved it.. right... When I take the rubber gasket off, I see there is only one contact? Meaning only one wire will actually connect to something, and if I remember correctly there was two on the car I took the plug from. So how could this be? The contact doesn't look broken, it's a white plastic plug with a contact sticking out, connecting only the black wire. Anyone ever encountered this? Is this the right switch I'm looking at? Any suggestions?

It never ends, but it's fun as long as it's cheap.

 

One wire is a kickdown and the other is a switch for the emission control solenoid..........forget about that one, and just run a vac hose directly from the dist advance to the nipple on your carb.

As for the kickdown, with the motor not running and in park, connect a test lite to the wire and ground the other end. When you floor it, it should light. If not, check the switch by the gas pedal and it's wiring.

If it lights, the problem is in the tranny.......try removing the pan, and take out the downshift solenoid and clean it well........it may be sludged up. This happened to me once.

As for having only one wire, it may be from an earlier car that didn't use 2 terminals. I think that emission switch was '71 and '72 only but I'm not certain about that. Hope I helped you. :bglasses:

 

Thanks guys, I'll get in there on Friday and have a look. The contact that is left is for the black cable, the one that comes back up over the transmission and then gets taped back together with a bunch of cables going through the firewall. The red one goes forward over the engine and the dives under it in the font, I suppose that is the smog something cable. The lack one was the one tat was broken, so just plugging a replacement back in didn't do it I guess. Now this black wire is supposed to hook up to a solenoid in the transmission, which is accessed by removing the pan? It also connect to a contac/switch which is hooked up to the gas pedal? I'll start with the light test, and if that doesn't do it, I'll go after the switch by the gas pedal, then the solenoid.

Thanks alot, it's looking better and better evey day.


Just a little fill in information... I bought the car from an Aamco transmission shop, don't you think they would take care of stuff like this if they're rebuilding the transmission? Just looping back the broken cable and pretending nothing has happened kind of tells me the level of workmanship offered. Also the pan covering the flywheel was missing one bolt, had one 10mm bolt halfway screwed in and two correct bolts. Ehhh, missing some bolts here, ehhh I'll just stick this one in here I found on the floor, and leave one missing, it wil be alright ehhh... ou:

 

10 mm bolt? The car's a 1972 model? I had a 1973 Riviera, and that had exactly zero metric fasteners that I ever saw...