I am getting ready to change the fluid in the transfer case and heard that dirty/grungy speed sensors located on or near the case will cause the transmission to shift rough. Currently, the transmission feels like it takes up a little slack from a dead stop before engaging and moving forward. So, I have a couple of questions:


Has any one heard of dirty/grungy sensors causing the symptoms I am experiencing?


If so, how many are there and where are they located?


Any special tricks or tips to servicing transfer cases & flushing the fluid?


Rear seal replacement tips?


Thank you.

on the 4l80e trans ther are two speed sensors. there is an input and an output. both are on the drivers side of the trans. the input is near the bell housing and the output isnear the tail unless you have a 4x4 and the output is on the transfer case. they look identical but i'm not sure of part #s as i replaced mine at different times. very easy to replace with a 10mm.i dont know about cleaning them but at $30 each replace them both they will go bad eventually anyway.


rear seal- use seal puller to pry out and use block of wood to drive new in.

I'm in the middle of changing the fluid now and found the rear seal is an assembly containing an outer rubber sheath and an interior seal. The assembly pops out of the back of the housing. The replacement seal I have will not work, so it is back to the parts store, this time with the exact part in hand.


BTW, I found two sensors on the tail housing of the auto-trac transfer case. I have not located the front speed sensor. I'll go ahead and snap some pictures if anybody is interested in what the seal looks like and any other info I can provide.