Eaton doesn’t range shift to high

[terex herder]

Eaton FR 15210B in 2006 Sterling. When shifting to high, sometimes won't make shift. Air blows out from under air module while shifter is in neutral, stops when shifter is in gear, but transmission isn't in gear. Do I just need to replace the air module, or is there something else I should check first?

 

[Truck Shop]

FR series should have control slave on top of shift bar housing on right front. You say sometimes
won't shift to high? but when it does it is in high range?
*
One issue with range shift on FR series is the range cylinder shift bar. There are two snap rings
to keep it centered, if those break which does happen it will not shift to high range. Can viewed
on page 5. The other is the low/high range synchronizer hub has lost it's lining material or slider
pins within hub broke, it can also cause same issue. But main thing is the shift module on shift
bar housing is working properly.
*

https://www.eaton.com/content/dam/eaton/products/transmissions/vehicle-transmissions/illustrated-parts-lists/eaton-fro-16210b-transmission-illustrated-parts-list-en-us.pdf

 

[Truck Shop]

Must have been another AI--scammer post, never came back.

 

[terex herder]

Thanks TS, I'm slow on a good day. No artificial here, nor intelligence.

 

[terex herder]

Back to this truck. I installed a new air module, still won't shift properly. I removed the shift bar housing and checked all the range cylinder parts and don't find a problem.

Any advise for a dabbler before I remove the auxiliary section in the truck?

 

[TVA]

Check the fork.
Can you actually hear clanking inside transmission, when trying to shift?
It’s pretty distinguishable on hi/lo.
You can move driveline, to eliminate hitting on top of teeth. That’s of course if those teeth in “shiftable” condition.

 

[stinky64]

If you can't hear the clanking when cycling splitter switch, check air supply line to air module. If you've got a low spot in the supply there may be ice in it restricting air supply. Playing with trucks in the great white north have seen this many times. Another remedy if air supply is good and module is sticking during warm months is to disconnect air supply (bleed pressure down first) and introduce generous supply of air tool oil, marvel mystery oil etc. to module and cycle a bunch of times until works like supposed to. Have done that one many times as well. Then there's splitting module and replacing o-rings if you've got them handy. The joys of fleet work. Something to consider.