I changed the settings on my Edge to view the TSS and OSS. My understanding is that they should relatively the same number (within reason) otherwise it indicates slippage in your tranny. I would expect them to be almost exactly the same number when you are cruising on level ground without load or tow. Mine is showing a variance of about 50%.
Is this an indication that my tranny is starting to fail and requires some work?

Thanks for your thoughts!

 

In first gear the turbine shaft speed will be about 2.88 times the output shaft speed.

In second gear, the TSS will be about 1.55 times OSS.

In third gear, they will be the same.

In fourth, the TSS will be LESS than the OSS because of the .71:1 overdrive.

When the torque converter clutch is applied, the engine RPM should always just about match the TSS.

The sensor inputs to the PCM have to do with the gear ratios in the transmission and the computer's way of self-diagnosis to determine whether or not there is slippage and whether or not the commanded shift actually took place.


Or to put it another way:

Engine --> [Converter] --> Input Shaft --> [Tranmission] --> Output Shaft

or more specifically...

Engine --> Input Shaft --> Output Shaft

-----------------------------------------------

Engine --> Input Shaft:

Same if Converter is locked
Different if Converter is unlocked (difference varies depending on load)
Input Shaft --> Output Shaft (Based on 4R75 Transmission)

1st gear - Input is 2.8387 x Output (2.8387:1)
2nd gear - Input is 1.5545 x Output (1.5545:1)
3rd gear - Input is the same as Output (1.0000:1)
4th gear - Input is 0.6984 x Output (0.9084:1)
Slip in the transmission can be easily calculated by finding the inpututput ratio and see if it matches the current ratio for the selected gear. If it doesn't match, then slip is present.

Slip in the converter is only determined during lockup.

 

thanks for the shotgun reply, Shotgunz! As those are all math equations to determine slip and computers are good at math so I am led to believe, Edge should incorporate that equation into their module so you can monitor slip in "real time". Be very simple i would think.

 

Sounds like a good idea to me. Why not suggest it to Edge?