1974 TH-400 Electrical Kick-down

[Paul L.]

I am trying to figure out how that switch near the gas pedal works for what used to be called passing gear. This 1974 350/195 with TH-400 is new to me and does not kick-down. I removed the transmission-controlled spark (TCS) solenoid as it appeared to have little function aside from some dubious benefits re emissions. Was that a mistake? I left the TCS wiring intact and can get it back in place very quickly. Does this system need the brake pedal switch, TCS solenoid at the manifold, and TCS switch at the transmission all in place to get "passing gear"?

I've had a 1979 (TH-350) with a detent cable and have a 1967 with Powerglide (adjustable rod) but this electrical set-up baffles me. Help!

[Jim T.]

Re: 1974 TH-400 Electrical Kick-down

Paul the kickdown switch activated by fully depressing the gas pedal is connected to the transmission. Have you examined the drivers side of the transmission and confirmed the wiring to the transmission is connected? I have a 70 turbo 400 that the kickdown function still works great now through its 38th year.

[Harmon C.]

Re: 1974 TH-400 Electrical Kick-down

The switch on the gas pedal on an automatic should have two plugs on it. One for the hood solinoid and the other for the kickdown. The kickdown plug has male ends on one side and female on the other. Check to see if the swich is adjusted to operate the solinoid and both plugs are installed.

[Paul L.]

Re: 1974 TH-400 Electrical Kick-down

OK, Jim and Lyle. I guess that I have a problem. As well as removing the intake TCS solenoid, I took out the cowl motor/solenoid/flapper as well. The cowl intake is now open. It seemed like a logical thing to do. Perhaps not! So I may have electrical dead-ends. In my ignorance of this machine I could not see a relationship between a hood cowl intake and a transmission?? Is there a manual detent cable setup for a TH-400?

[Harmon C.]

Re: 1974 TH-400 Electrical Kick-down

Not having the hood flapper in line should not be a problem but the switch must work. The TCS on the intake is not needed either. Remove the switch from the transmission and check it and the wire lead to it would be a good place to start. A wireing diagram would help the most.

[Paul L.]

Re: 1974 TH-400 Electrical Kick-down

Not having the hood flapper in line should not be a problem but the switch must work. The TCS on the intake is not needed either. Remove the switch from the transmission and check it and the wire lead to it would be a good place to start. A wireing diagram would help the most.

I have a wiring diagram and the shop manual. A friend has a hoist so we''ll check out the transmission end shortly. Thanks.

[Paul L.]

Re: 1974 TH-400 Electrical Kick-down

Jack Humphrey sent me a very imformative message on this subject. Jack, thank you!