'07 Century w/Eaton SmartShift (Auto) Problem

Here's the truck: 2007 Century S/T w/ a CAT C-15 pushing an Eaton 10-speed SmartShift automatic tranny.

Here's the issue: You apply the service brake and drop the truck into D and the truck goes into gear the first time, no problem. However, if you put it back into neutral and then try to put it in D again, the truck remains in neutral and beeps at you as it would if you did NOT apply the service brake and tried to put it in gear.

Here's what we've done so far:

1. Tested all sensors – good
2. Checked all circuits in the J1949 bus - good
3. Cleaned all interface connections in the electrical bus – no change
4. Swapped the truck ECM – no change
5. Swapped the tranny ECU – no change
6. Swapped the X-Y shifter (Eaton K3784) – no change
7. Swapped the transmission shifter module on the steering column – no change

Here's where we're at: No fault codes are recorded on either the CatET or the RoadRanger diagnostic tools. We’re 5 days into this now and no closer to a solution than when we started. We’ve thoroughly followed the “Will Not Engage a Gear from Neutral Test” straight out of the Eaton manual to no avail.


Here's what we need: Some expert-level advice, meaning someone more advanced than me and my team who may have experienced and/or resolved this or a similar issue, to point us in the right direction.

Thanks in advance for any responses.

 

Solid (not blinking) N and the beeping, exactly as it would react if you tried to put it in gear without having the service brake applied.

Thanks

 

Good points. Have tested both the input and output shaft speed sensors physically and with Service Ranger. Both the ECM and TCU have been swapped with known good units and all circuits in the bus have checked out. All interfaces have been cleaned and inspected. New clutch in May. Inertia brake tests good. It's a bit of work, but I'm going to have the crew swap out the shifter forks assembly that the X-Y Shifter sits on top of. Maybe that one of the forks or shaft is out of tolerance.

Any other advice is welcome! Thanks in advance.

John

 

SOLVED

Replaced transmission forks assembly - a.k.a. "Shift Bar Housing" and the issue was resolved. Apparently, part or parts unknown had wear outside of tolerance. However, since Eaton does not make a maintenance kit for that assembly, I holstered my digital caliper and opted for a very dry martini... and when I say "dry", I mean parched... arid... unmoistened. Dry, like I poured the vodka into the glass and very briefly considered the word "vermouth" as I took the first sip.

Anyway, thanks for all the tips - I really appreciate it.