Eaton 9 Speed splitter problem

I hate to be a jerk and say this, but it's range not splitter. Splitter is on 13 and 18 speeds. Range is in all transmissions that use the shift pattern twice. Yes, don't mention super 10s because they're completely different.

Anyway, to your issue, there a range interlock that prevents this from happening. It sounds like yours is broken, and it shifts as soon as you lift the paddle.

 

I think the interlock valve is on top. You should be able to get the parts from your parts dealer.

Your transmission isn't a Rockwell or Meritor?

 

I looked at a service manual. The interlock is a mechanical device that prevents air from activating the slave cylinder. The file is too big to share, and I can't copy the link. Google Eaton service manual trsm0515 and look on page 21. I think you will need to pull the tower and rebuild the interlock. If that is something that you can't do now, would you trust yourself enough not to preselect the range? If so, the problem is not in the box, so it shouldn't cause any damage, as long as you never preselect the range shift.

 

So often we shift by habit. I time the flip so I am still in neutral, shifting into fourth, but have cleared the interlock. I know that is earlier than necessary, but I do it automatically.

 

The range air control valve is on the left side of the transmission just below gasket of the top plate. There is a plunger in the main case between that valve and the top plate shift rails. It will not allow the range valve to shift unless the shift rails are in neutral. When installing the top plate it has to be off to the right side then pushed to the left depressing the plunger. If the top is slapped down on top of the plunger and bolts tightened it is locked down, if in the correct position range can try to shift at any time. Even if you cannot get the top off in your truck it should be possible to remove all the top plate bolts and move it to the right. Slide it back to the left and install a couple bolts and see if it works. If the bore or the plunger is mucked up you may have to remove the air valve. Work on the bore a bit and maybe replace the plunger.