Thanks for your help, clinebarger. I have very little experience with automatic transmissions, so any help is most welcome.
The subject truck is a 2006 Freightliner M2 with an Allison 2100 HS tranny. There is no TCC slip pid in the data stream. There is engine speed, turbine speed and output speed pids. Yesterday I graphed engine speed and turbine speed while driving along a 20mph with the clutch test enabled for 2nd gear and the variation with the two speeds while I stepped on the throttle indicates that the TCC was not applied.
The TCC solenoid passes the solenoid test in Allison DOC.
I don't think there are any codes in the TCM but I will check again.
Truck is not giving any issues but I was just curious as to whether the TCC was working as it should.