4L60E Problem, Different than any I have seen

[jkolkind]

Hey there,
I have been doing a lot of looking but cant find anyone that has had this problem, so hopefully someone can tell me what they think is going on.
I have a 94 2wd c1500. I am just turning 70,000 miles on it. The transmission just started to act up.

if I put the selector in drive or OD, when I take off, it shifts very soon. it doesnt start in second though. It used to shift hard between 1 and 2 (common on these I have found). When I noticed this problem I stopped, put the selector in 1st, and tried it.

If selector is in first, the truck will drive, no slipping, but if you let off it is like the brakes are on, the truck will come to a quick stop. On ice, the tires lock up when you let off.

Put the selector in second, truck rolls just fine.

Put the selector in 1st again, let off brake, and it creeps, then feels like something kicks in after a couple seconds and it stops until you give it gas.

Other than that, it shifts fine. So i tried to make it downshift.

Let it shift to second, and then put it to the floor, it downshifts to first, and then immediately goes back into second, (not hard into second, more of a slide in). anyone have any ideas, tried to do my best to explain, and any help is appreciated. I am a mechanic, but not a tranny guy....anyone??

[MT-2500]

You may have some valve body valve/gasket or servo problems.
Has it ever been worked on or any shift kit stuff put in it.
Make sure the shift linkage inside and out and shift valve is centered good.
And drop the pan and check for any extra metal or clutches in the bottom of pan

Also get a transmission capable scanner on it and check it out good on the computer stuff and codes.

Here is a link to a good transmission forum if you want to run a post there and ask for transman he may have some more ideas on it.
http://www.batauto.com/Forums/index.php?board=5.0

Good Luck
MT

[Danielswan]

ya. sounds like the servo is applying the band when it is not supposed to. should get it scanned. other then electrical issues there are many things that can cause this. seperator plate damage, gaskets leaking, servo wear, or some check balls could be damaged or stuck.