No 4th gear despite rebuild.

[J444HN]

i had my transmission rebuilt due to it slipping in 1st and 2nd.
I bought a rebuilt box and it wouldn’t shift properly so just had my original rebuilt and fitted.

The transmission shop had a nightmare with it and couldn’t get it to go into 4th and it’s flaring between 2-3rd. It also seems to take a while to ‘grab’ 1st when pulling away.
The tcm appears to be commanding 4th but it simply isn’t shifting. The box has been bench tested with air and everything moves as it should when the air is applied i.e the sprag releases or whatever it is. It had a remanafactured valve body fitted as recommended by the trans ship but it’s still does the same.

Any ideas on what to try next?
I’m stumped with this.
Fluid levels etc all ok. The trans shop said they’ve ‘checked’ everything.

 

[HiHoeSilver]

i had my transmission rebuilt due to it slipping in 1st and 2nd.
I bought a rebuilt box and it wouldn’t shift properly so just had my original rebuilt and fitted.

The transmission shop had a nightmare with it and couldn’t get it to go into 4th and it’s flaring between 2-3rd. It also seems to take a while to ‘grab’ 1st when pulling away.
The tcm appears to be commanding 4th but it simply isn’t shifting. The box has been bench tested with air and everything moves as it should when the air is applied i.e the sprag releases or whatever it is. It had a remanafactured valve body fitted as recommended by the trans ship but it’s still does the same.

Any ideas on what to try next?
I’m stumped with this.
Fluid levels etc all ok. The trans shop said they’ve ‘checked’ everything.

Just my .02 here, but "checked everything" doesn't fly in my book. Did they install it, or just build it? If they did the install, I'd make them figure it out. If that means building it again, then so be it.

 

[J444HN]

They built and fitted it. They said they’ve redone it 3 times now.
Apparently.

 

[swathdiver]

There are a number things it could be, the most likely for 4th not engaging are the valve body checkballs in the wrong or missing or extra positions. Could also be the Orificed Cup Plug not fully pressed into the pump cover. Flaring between gears is often to do with the Pump Slide Spring.

A Tech2 can check a lot of internal functions of the transmission. Every man ought to have one that intends to own one of these trucks.

 

[Rick Simons]

+1 on the above replies. A good scanner can be used to activate and test the various solenoids. If I paid someone to do my trans I would surely insist that they made it right. As mentioned above it only takes one check ball out of place......

 

[UrbanSuburban]

I agree with the above, plugging in a Bidirectional scan tool should get to the root of the problem, in fact your check engine light should be on, that should point you in the right direction.