Allison Clutch Test - What is it?

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I am attaching the two relevant pages from the Allison DOC User Manual about the Clutch Test. I do not understand what the purpose of the test is. I believe it tests the torque converter clutch. How does this test accomplish that?

Allison 1.jpg


allison 2.jpg
 
Allows you to test Clutch Holding ability & Solenoid combination/Shift Valve functionality. Selecting higher than normal commanded ratios allow easier diagnosis of slipping components.
 
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Originally Posted by clinebarger
Allows you to test Clutch Holding ability & Solenoid combination/Shift Valve functionality. Selecting higher than normal commanded ratios allow easier diagnosis of slipping components.


That's about it! Tip-tronic with a little more control, basically.
 
So how would I actually test for a slipping TCC? Drive along at a steady 40mph, select 5th (Drive) in the Clutch Test Mode and then see if the engine flares up if I step on the throttle? The Engine and Turbine speeds are displayed on Allison DOC, so I could watch that to see if the clutch is slipping. Is there another better way?
 
I'm not familiar with commercial Non-GM Allison applications, In a GM application....There is a TCC Slip RPM data PID that tells you everything you need to know. It basically takes the Turbine speed & Engine speed & displays the differential.

Do you have TCC Slip code/s in the TCM?
 
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.
 
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