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06-30-2019, 05:56 PM
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#1 |
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Junior Member
 Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Th400 shift problem
Sensor that threads into valve body leaking fluid and pressure. I can't find one listed anywhere. Anyone know the part number, or where to get one? Thanks.
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06-30-2019, 08:15 PM
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#2 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,280
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Re: Th400 shift problem
How about a picture?
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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06-30-2019, 08:26 PM
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#3 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
I'll try. I got the picture, just have to see if I can post it. I put a screw in the sensor to block it off and am going to reinstall the valve body and see what happens. It is accessible without removing the valve body, so I won't be any worse off than I am now. Thanks. Nope, this site wants the url of my image, whatever that is. I can email it to you.
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06-30-2019, 08:31 PM
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#4 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
https://photos.app.goo.gl/gnJWm9ZujZVphdqr8. That's supposed to be a link to my photo of the sensor.
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06-30-2019, 08:32 PM
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#5 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
Hey, hey, hey, I clicked on it and it came right up with my sensor.
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06-30-2019, 09:08 PM
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#6 |
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Senior Member
Join Date: Mar 2003
Location: Colfax-California
Posts: 8,480
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Re: Th400 shift problem
I've had A LOT of T400s apart and never seen that sensor. What is that for? either than removing it and putting a plug in the hole
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06-30-2019, 09:44 PM
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#7 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
The wire from the internal shift solenoid goes on that end where the wire clips on. I'm not a transmission mechanic, so I have no idea. This transmission is supposed to be overhauled. I bought the truck as a put back together project and almost EVERYTHING has been wrong with it. The trans doesn't shift out of low, so I was inspecting the valve body and just pushed on the servo piston with my hand and it sauirted fluid out the end of the sensor. I took the sensor out and could blow air through it almost like there was no center in it. I'm gonna look for a plug and just plug it up, but if I can't find one , I'm just gonna plug the sensor with a screw. Good luck to me.....lol
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06-30-2019, 09:49 PM
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#8 |
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At the body shop.
Join Date: Aug 2009
Location: Land of fruits and nuts.
Posts: 5,192
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Re: Th400 shift problem
It needs vacuum to shift. The kick down deal isn't really needed unless you cant pull the lever down
__________________
" That didnt make it any newer " " Dont antique the equipment " |
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06-30-2019, 09:57 PM
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#9 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
Yep, new modulator, removed governor,, checked vacuum line, removed valve body, and accidentally found that leaking sensor, so it can't shift if it's losing it's pressure. I'll see what happens.
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06-30-2019, 10:03 PM
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#10 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
Just got back under the truck, and the wire from that sensor goes to the plug that goes through the case to hooks to the kickdown harness. Maybe this trans was in something that had a temp gauge???????
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06-30-2019, 11:35 PM
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#11 |
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At the body shop.
Join Date: Aug 2009
Location: Land of fruits and nuts.
Posts: 5,192
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Re: Th400 shift problem
Mine was acting stupid. And found a vacuum leak between the carb and modulator
__________________
" That didnt make it any newer " " Dont antique the equipment " |
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07-01-2019, 12:37 AM
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#12 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
I was reading my instruction sheet for a B&M shift kit and it said that sensor is a pressure switch.
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07-01-2019, 01:37 AM
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#13 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
OK, guys....I appreciate your input. I was on another site and the pressure switch in my valve body is probably for a Transmission Controlled Spark system. It is not necessary to connect it to the electrical system. I would recommend removing it and plugging the hole if your vehicle does not have TCS. Just to avoid the pressure leaking I experienced with mine.
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07-01-2019, 08:52 AM
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#14 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,280
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Re: Th400 shift problem
That's good to know. Did that turn out to be the problem?
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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07-01-2019, 09:48 AM
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#15 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
Don't know yet. I got it all back together this morning at 1am . I've got to work today, so it'll be the weekend again 'til I get back to it. Y'all have a great week!!
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07-01-2019, 09:51 AM
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#16 |
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Junior Member
Join Date: Nov 2018
Location: Kirkwood, PA
Posts: 97
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Re: Th400 shift problem
That would be a neat way to mount a temperature sensor, and most of the wiring is done.
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07-01-2019, 12:44 PM
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#17 |
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Who Changed This?
Join Date: Jan 2013
Location: Simi Valley, CA
Posts: 10,280
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Re: Th400 shift problem
Yes, that would be a nice clean install.
__________________
~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA |
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