electronic kickdown solenoid in th400 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chugger · 01-11-2005, 12:48 PM

do you need a 12 volt constant or just activated at kickdown my tranny is stuck in 2nd gear and cant figure out if its this or the vacuum kickdown or the homemade linkeage for the b&m are exactly right? I went from a 3 on the tree to a th400 can someone please help.
every other gear works except for the forward gears.

ac102nv · 01-11-2005, 01:15 PM

You only want 12v to the trans for kickdown, not all the time. However, this sounds more like a linkage/internal problem. If the trans has 12v all the time or no vacuum it would not want to shift out of first until RPM's are high. I would start with your homemade linkage and make sure it is working correctly.

Bob Moore · 01-11-2005, 01:18 PM

The lead going to the switch is always hot with key in run position. The switch activation completes the circuit to the tranny. Pink wire to the switch from the fuse block and orange from the switch to the tranny.

Disconnect your wiring to check the tranny operation. If it works properly then your wiring is messed up.

53 Chevy · 01-11-2005, 02:41 PM

Check And Make Sure You Have Vacuum To The Modulator.

Chugger · 01-12-2005, 08:06 AM

problem solved it was the vacuum modulator.
thanks guys
lata
chris

01-11-2005, 12:48 PM	#1
Chugger Registered User Join Date: Nov 2004 Posts: 18	electronic kickdown solenoid in th400 do you need a 12 volt constant or just activated at kickdown my tranny is stuck in 2nd gear and cant figure out if its this or the vacuum kickdown or the homemade linkeage for the b&m are exactly right? I went from a 3 on the tree to a th400 can someone please help. every other gear works except for the forward gears.

01-11-2005, 01:15 PM	#2
ac102nv Registered User Join Date: Jul 2004 Location: Northern Nevada Posts: 156	You only want 12v to the trans for kickdown, not all the time. However, this sounds more like a linkage/internal problem. If the trans has 12v all the time or no vacuum it would not want to shift out of first until RPM's are high. I would start with your homemade linkage and make sure it is working correctly. __________________ '72 C10 lwb 454/TH400

01-11-2005, 01:18 PM	#3
Bob Moore Registered User Join Date: Feb 2004 Location: Tacoma WA Posts: 1,365	T-400 The lead going to the switch is always hot with key in run position. The switch activation completes the circuit to the tranny. Pink wire to the switch from the fuse block and orange from the switch to the tranny. Disconnect your wiring to check the tranny operation. If it works properly then your wiring is messed up. __________________ 67 C-20 LWB, tilt, speed alert, vac, 454, T400 67 C-10 SWB, factory air with more to follow

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01-11-2005, 02:41 PM	#4
53 Chevy Registered User Join Date: Jan 2005 Location: WEST CENTRAL GEORGIA Posts: 30	Check And Make Sure You Have Vacuum To The Modulator.

01-12-2005, 08:06 AM	#5
Chugger Registered User Join Date: Nov 2004 Posts: 18	problem solved it was the vacuum modulator. thanks guys lata chris



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