Shifting at high RPM

[cadillac_al]

If it was mine, and the trans was getting full vacuum, and a new vacuum modulator makes no difference, I would buy a Transgo shift reprogramming kit. When replacing the springs in the valve body valves I'll bet I would find a stuck valve even though I have never seen it happen before. Maybe it has a stuck or broken spring. I still think it will be something simple when you find it. just my .02

[Captain J]

Originally Posted by cadillac_al

If it was mine, and the trans was getting full vacuum, and a new vacuum modulator makes no difference, I would buy a Transgo shift reprogramming kit. When replacing the springs in the valve body valves I'll bet I would find a stuck valve even though I have never seen it happen before. Maybe it has a stuck or broken spring. I still think it will be something simple when you find it. just my .02

We don’t have such kit, and no one knows how to do it.

[Shifty One]

Originally Posted by cadillac_al

I still think it will be something simple when you find it. just my .02

Agreed.

[Captain J]

Originally Posted by Shifty One

Agreed.

Always the simple and obvious things get you
But what is?


I’m still waiting to know the reason of oil spillage?

[kwmech]

Oil level in the transmission while running is approximately at the oil pan gasket level. Vacuum Modulator is above the pan. If the truck sits for any amount of time the torque convertor will drain out some raising the level in the pan until you start the truck again. So to answer your question...it depends.

[Captain J]

Originally Posted by kwmech

Oil level in the transmission while running is approximately at the oil pan gasket level. Vacuum Modulator is above the pan. If the truck sits for any amount of time the torque convertor will drain out some raising the level in the pan until you start the truck again. So to answer your question...it depends.

It’s possible,
But still the issue isn’t resolved

[Dead Parrot]

Don't think it was ever mentioned but does it do fine in reverse? And switch properly from reverse to drive and back? Its just not going from 1st to 2nd to 3rd?

In case you missed it, there is a sticky tread on the TH400 under the Engine and Drivetrain section. Might be helpful if you have to dig deeper.

[Captain J]

Originally Posted by Dead Parrot

Don't think it was ever mentioned but does it do fine in reverse? And switch properly from reverse to drive and back? Its just not going from 1st to 2nd to 3rd?

It shifts fine between all gears, P R N D 1 2. Only when driving it will not shift from 1st gear.

In case you missed it, there is a sticky tread on the TH400 under the Engine and Drivetrain section. Might be helpful if you have to dig deeper.

Don’t know that, do you have a picture to show it? I mean the sticky tread?

[geezer#99]

Possibly it’s the detent switch that’s the culprit.
Says that in my motors manual.
Here’s a thread I found that might help.


http://67-72chevytrucks.com/vboard/s....php?p=7037666

[Captain J]

Originally Posted by geezer#99

Possibly it’s the detent switch that’s the culprit.
Says that in my motors manual.
Here’s a thread I found that might help.


http://67-72chevytrucks.com/vboard/s....php?p=7037666

I looked at your thread, but it’s beyond my expertise.

I asked one garage that says he is expert in transportations he said “ you need to replace your trans cuz your clutches are gone!!!!, but I’ve a used one to sell?”
How stupid he thinks!
If clutches are gone, trans will not shift, or it will slip.

So I’m searching for a solution.
Thanks for the info

[geezer#99]

Did you try to just unplug the connector on the detent switch and then test it?

[Captain J]

Originally Posted by geezer#99

Did you try to just unplug the connector on the detent switch and then test it?

No I didn’t not, I read the thread you sent, it involves some testing which I don’t know how, plus I’m not sure of the location (detent switch), and I don’t want to screw up

If it’s the kickdown switch by the gas paddle, that has a single wire connected to left side (driver side), yes I disconnect it, drove the truck, nothing it’ll not shift.

I appreciate your help

[geezer#99]

Bypass everything and unplug it on the transmission.
The switch is on the drivers side at the back.
Pic in here.


https://www.gm***************/thread...kickdown.1107/

[Captain J]

Originally Posted by geezer#99

Bypass everything and unplug it on the transmission.
The switch is on the drivers side at the back.
Pic in here.


https://www.gm***************/thread...kickdown.1107/

Pic not available

[geezer#99]

Try this.


https://www.gtoforum.com/threads/hel...140685&slide=0

[Captain J]

Originally Posted by geezer#99

Try this.


https://www.gtoforum.com/threads/hel...140685&slide=0

I didn’t see a connector similar to the pic on the right side (driver side)
The only connector is coming from the 4x4 firewall to the top left side, I think it’s for 4x4 engagement and light,
See pictures

[Captain J]

Originally Posted by Captain J

I didn’t see a connector similar to the pic on the right side (driver side)
The only connector is coming from the 4x4 firewall to the top left side, I think it’s for 4x4 engagement and light,
See pictures

Here are the pictures
Hopefully I can load it

[Captain J]

Originally Posted by Captain J

Here are the pictures
Hopefully I can load it

Pictures are attached,
The website will not allow me to upload more than 2, or it keeps say your message is toooooo short

[geezer#99]

Originally Posted by Captain J

Here are the pictures
Hopefully I can load it

That first pic shows the switch.

[Captain J]

Originally Posted by geezer#99

That first pic shows the switch.

I did disconnected it, as I mentioned before, nothing.

[GRADYS Performance]

Originally Posted by Captain J

Here are the pictures
Hopefully I can load it

Did you disconnect the orange wire that went to the transmission in this picture?

[Captain J]

Originally Posted by GRADYS Performance

Did you disconnect the orange wire that went to the transmission in this picture?

Yes I did and nothing still will not shift from 1st gear

[Captain J]

Any ideas?
I’m not getting any luck with this trans.
I managed to get me a vacuum gauge but I’m not sure what to do or to look for?
Any suggestions

[Captain J]

Greetings to you all for helping out in my truck gear issue.
Update
I test drive the truck last night, and it shifts in all gears, I don’t know what happened, but it’s working fine,
Again, thank you all for your suggestions and recommendations, I wish I knew what was wrong with the tranny.

[kwmech]

Probably a piece of that silicone