Th400 kickdown again!
Thread Starter
Instructor
Joined: Dec 2007
Posts: 245
Likes: 2
From: Jersey shore NJ
Th400 kickdown again!
Hi Guys, I've been chasing down this problem of my TH400 not kicking down.
I have already check the switch and it seems to be working.
I tied a string to the switch and drove the car and used the string to activate the switch so I know it was being triggered.
The trans does not want to kick down all the time and when it does it usually wants to up shift right away.
I was testing this at speeds below 45mph.
Any thoughts on what to check now.
I changed the modulator already.
Thanks Jim
I have already check the switch and it seems to be working.
I tied a string to the switch and drove the car and used the string to activate the switch so I know it was being triggered.
The trans does not want to kick down all the time and when it does it usually wants to up shift right away.
I was testing this at speeds below 45mph.
Any thoughts on what to check now.
I changed the modulator already.
Thanks Jim
Melting Slicks
Joined: Jan 2003
Posts: 2,877
Likes: 13
From: Doha
St. Jude Donor '08
Have you tried to adjust the modulator? .. try to rotate the small screw inside the tube and see if that would change anything. I don't know much about transmissions, but its a small thing that you may try.
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
engine off,
switch on
press the pedal
if the solenoid in the tranny clicks, the electronics that make it kick down are good. i was under the impression that engine vacuum doesnt make the kickdown work.
switch on
press the pedal
if the solenoid in the tranny clicks, the electronics that make it kick down are good. i was under the impression that engine vacuum doesnt make the kickdown work.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 245
Likes: 2
From: Jersey shore NJ
Thanks Guys, yes I put in a new modulator and have played with the screw adjustment just to try and get the gears to wine out a little longer.
And the switch is working, I can hear it click and it does sometimes downshift, but not everytime.
And the switch is working, I can hear it click and it does sometimes downshift, but not everytime.
Instructor
Joined: May 2003
Posts: 128
Likes: 1
From: Lake Geneva WI
My '75 never downshifted since I bought it in 1995. Never really tried to repair it as there was so much other stuff to do. A couple of years ago I took the leaking trans pan off to put in a new filter and gasket and when I got everything off I noticed a wire hanging inside the trans disconnected from its' terminal, also enclosed inside the trans. I reconnected the wire, put everything backtogether and when I was done the car would downshift. I have no idea how this connection came apart, whether by vibration or an absent minded mechanic, but apparently it controls the downshift operation. No shift problems since. Trans (TB400) still drips.
