TH400 kickdown wiring question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

glock35ipsc · 05-05-2007, 05:38 PM

The kickdown on Dad's 72 doesn't work. It has the switch on the gas pedal; the pink runs to the fuse block, and the yelloe rund through the firewall. Under the hood, the yellow wire ends about 10"-12" from the firewall with a factory spade connector on it. Nothing that I can see that it should plug into.

Down on the tranny, there is a sensor or ?? right near the shift linkage with nothing attached to it. I think it had two terminals on it.

My wiring diagram doesn't show any wiring for a TH 400. Can anyone tell me how this needs to be wired?

Thanks!

gator2511 · 05-05-2007, 06:33 PM

My TH400 has a hot wire going to the kickdown switch. When the switch is activated the switch makes contact and sends 12 volts down to the tranny solenoid. The solenoid is located on the driver side of the tranny near the gear selector linkage. You found it, its just not a sensor. The hot wire plugs onto the terminal on the solenoid and kicks the tranny down into passing gear. It goes to ground to complete the circuit through the transmission case. It should have only one terminal on it.

JimKshortstep4x4 · 05-05-2007, 06:57 PM

The 72 was probably set up with the TCS system and the extra spade would be for the signal to the TCS that the tranny was in high gear. The terminals
look like a "T" when looking at the detent switch, (one spade is vertical and the other is horozontal). The vertical spade is the detent switch connection.

Jim

gator2511 · 05-05-2007, 07:10 PM

Quote:

Originally Posted by JimKshortstep4x4

The 72 was probably set up with the TCS system and the extra spade would be for the signal to the TCS that the tranny was in high gear. The terminals
look like a "T" when looking at the detent switch, (one spade is vertical and the other is horozontal). The vertical spade is the detent switch connection.

Jim

Thanks for helping keep me straight!

JimKshortstep4x4 · 05-05-2007, 07:16 PM

gator2511,

It is easy to forget about the TCS setup on these trucks as most have long been removed!

Jim

glock35ipsc · 05-05-2007, 07:29 PM

Thanks guys! We'll get it hooked back up tomorrow then.

05-05-2007, 05:38 PM	#1
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	TH400 kickdown wiring question The kickdown on Dad's 72 doesn't work. It has the switch on the gas pedal; the pink runs to the fuse block, and the yelloe rund through the firewall. Under the hood, the yellow wire ends about 10"-12" from the firewall with a factory spade connector on it. Nothing that I can see that it should plug into. Down on the tranny, there is a sensor or ?? right near the shift linkage with nothing attached to it. I think it had two terminals on it. My wiring diagram doesn't show any wiring for a TH 400. Can anyone tell me how this needs to be wired? Thanks! __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE

05-05-2007, 06:33 PM	#2
gator2511 Registered User Join Date: Mar 2005 Location: tampa florida Posts: 776	Re: TH400 kickdown wiring question My TH400 has a hot wire going to the kickdown switch. When the switch is activated the switch makes contact and sends 12 volts down to the tranny solenoid. The solenoid is located on the driver side of the tranny near the gear selector linkage. You found it, its just not a sensor. The hot wire plugs onto the terminal on the solenoid and kicks the tranny down into passing gear. It goes to ground to complete the circuit through the transmission case. It should have only one terminal on it.

05-05-2007, 06:57 PM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: TH400 kickdown wiring question The 72 was probably set up with the TCS system and the extra spade would be for the signal to the TCS that the tranny was in high gear. The terminals look like a "T" when looking at the detent switch, (one spade is vertical and the other is horozontal). The vertical spade is the detent switch connection. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

05-05-2007, 07:16 PM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: TH400 kickdown wiring question gator2511, It is easy to forget about the TCS setup on these trucks as most have long been removed! Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC

05-05-2007, 07:29 PM	#6
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,685	Re: TH400 kickdown wiring question Thanks guys! We'll get it hooked back up tomorrow then. __________________ *Bob* 1970 Chevy K10 LWB "Goldie" 350/TH350 *next project!!* 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE



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