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

**RenoKeene** · 08-13-2012, 12:46 PM

Does anyone have pics or a wiring diagram of the wiring harness for a 72 th400 kickdown switch, the one that mounts to the gas pedal bracket in the cab? My wiring harness seems to be too short.
Thanks

davepl · 08-13-2012, 01:55 PM

This might help... 1970 though. IIRC, one wire goes to the trans and the other goes to the "IGN UNFUSED" terminal of the fuseblock, but you'll want to confirm that elsewhere.

Mine went to the carb, not the gas pedal. Unless they changed it from 70 to 72, that might be why it doesn't reach for you!

TH400 kickdown is 75% of the reason that I'm switching over to a TH200-4R. Not the wiring part, but I always found the kickdown on TH400s to be barbaric.

desertnick69 · 08-14-2012, 12:16 AM

I have 1969 350/400TH and its all ran of manifold vac.

**RenoKeene** · 08-14-2012, 08:27 AM

My truck is a 70 but the gas pedal/kickdown switch is 72 and the th400 is 74. I bought the wiring harness (for a 72) off a member here but it is too short to run from the gas pedal to the tranny thru the firewall to the sensor on the tranny.
I hope this is a little clearer...I need info on a 72 hookup, not a 70 and my 70 service manuel doesn't show the 72.
Thanks
I'll post a pic of what I have tomorrow.

68C10HotRod · 08-14-2012, 12:05 PM

Don't have a picture handy but plug one end into ignition spot in fuse box, the double blade connector plugs in at the gas pedal & the other longer end should plug into sensor on the transmission. All this does is pass power to the tranny when the pedal is depressed far enough for that slider to make a connection & complete the circuit. If the tranny side isn't long enough, just extend it. Hope this helps.

**RenoKeene** · 08-14-2012, 12:26 PM

Yes, thanks. This is how I have it but the wire from the kickdown switch to the tranny sensor is too short. I can splice another piece of wire into it to make it longer but I just wondered how what I bought was actually ever installed on a truck.
Thanks for the input....I'll make what I have work.

08-13-2012, 12:46 PM	#1
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,028	72 TH400 kickdown wiring Does anyone have pics or a wiring diagram of the wiring harness for a 72 th400 kickdown switch, the one that mounts to the gas pedal bracket in the cab? My wiring harness seems to be too short. Thanks __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

08-13-2012, 01:55 PM	#2
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: 72 TH400 kickdown wiring This might help... 1970 though. IIRC, one wire goes to the trans and the other goes to the "IGN UNFUSED" terminal of the fuseblock, but you'll want to confirm that elsewhere. Mine went to the carb, not the gas pedal. Unless they changed it from 70 to 72, that might be why it doesn't reach for you! TH400 kickdown is 75% of the reason that I'm switching over to a TH200-4R. Not the wiring part, but I always found the kickdown on TH400s to be barbaric. Attached Images __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

08-14-2012, 12:16 AM	#3
desertnick69 Registered User Join Date: Jan 2012 Location: Phoenix, Arizona Posts: 500	Re: 72 TH400 kickdown wiring I have 1969 350/400TH and its all ran of manifold vac.

08-14-2012, 08:27 AM	#4
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,028	Re: 72 TH400 kickdown wiring My truck is a 70 but the gas pedal/kickdown switch is 72 and the th400 is 74. I bought the wiring harness (for a 72) off a member here but it is too short to run from the gas pedal to the tranny thru the firewall to the sensor on the tranny. I hope this is a little clearer...I need info on a 72 hookup, not a 70 and my 70 service manuel doesn't show the 72. Thanks I'll post a pic of what I have tomorrow. __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

08-14-2012, 12:05 PM	#5
68C10HotRod Registered User Join Date: Feb 2008 Location: Omaha, NE 68144 Posts: 333	Re: 72 TH400 kickdown wiring Don't have a picture handy but plug one end into ignition spot in fuse box, the double blade connector plugs in at the gas pedal & the other longer end should plug into sensor on the transmission. All this does is pass power to the tranny when the pedal is depressed far enough for that slider to make a connection & complete the circuit. If the tranny side isn't long enough, just extend it. Hope this helps. __________________ Bryan '52 Bel Air 2dr HT - in pieces '68 C10 - 6cyl/4spd REMOVED, LT1/T56 to be installed “Any society that would give up a little liberty to gain a little security will deserve neither and lose both.” - Benjamin Franklin "And those who know what's best for us, Must rise and save us from ourselves" - RUSH lyric (mockery)

08-14-2012, 12:26 PM	#6
RenoKeene Florida Edition Join Date: Oct 2010 Location: Fruitland Park, FL Posts: 4,028	Re: 72 TH400 kickdown wiring Yes, thanks. This is how I have it but the wire from the kickdown switch to the tranny sensor is too short. I can splice another piece of wire into it to make it longer but I just wondered how what I bought was actually ever installed on a truck. Thanks for the input....I'll make what I have work. __________________ 70 GMC Short Stepside "Rose"-An American Beauty: Factory 402/TH400, AM/FM, AC, Tilt, Tach, Buckets, Posi, PS, PB, 3-5 Drop, Complete Resto-Rod 67 C-20 Slant Back Wrecker "Mad Max" 67 C-10 Ratrod "Step-N-Wolf" 71 Serro Scotty Sportsman camper "Scotty" 97 LT1 Z28 "The Hornet" Link to more pics of "Rose" http://67-72chevytrucks.com/vboard/a...p?albumid=1684 Check out my "Cheap Tricks" thread and add to it if you can, lots of good info there. http://67-72chevytrucks.com/vboard/s...d.php?t=489394

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