Mr. Brett

iTrader: (13)

I've got a 4L60E that was just built by a local builder with all the good hard parts and some modifications like the removed check ball on the input shaft, a Trans Go shift kit, etc. Standard build. Since day 1 it's had an intermittent lock up (usually locks up ok once it warms up) problem but everything else has been rock solid. Yesterday after doing some hard lanches for scanning, it started having some problems on the 1-2 shift. It revs to around 4k before it struggles to shift, and I'm pretty sure it's either skipping 2nd and going right to 3rd or just barely touching 2nd and then shifting into 3rd right away. It's also throwing a P0748 code (pressure control solenoid electrical). So my question is, could this be caused by a bad PCS or wiring harness? IE, low or sporatic line pressure? Any help is appreciated.

performabuilt

iTrader: (25)

Could be caused by presure issues but if your skipping second then you likley have damage to the band at this point,
I would pull pan and look around.

Mr. Brett

iTrader: (13)

Well, it might not be skipping second. Would a PCS explain the no lockup and slow 1-2 shift?

dnkynrbk

iTrader: (34)

I agree with Frank pull the pan and see if there is shavings in there if there is then you have tranny damage.

performabuilt

iTrader: (25)

Actually generally a PCS electrical code will cause quiet the oposite max line presure very harsh shifts. However anything is possible.

Mr. Brett

iTrader: (13)

That's what I thought too, but it doesn't seem to be going into limp mode. I'm gonna drop the pan tonight to see if there is any mechanical damage, but I stopped driving it as soon as it started slipping. I'm hoping it's just a pressure issue and there isn't any damage to hard parts.

Mr. Brett

iTrader: (13)

Found a bit of black powder in the pan, but nothing major. If I had a few more miles on the thing I'd almost consider it normal wear. I did verify that it has little to no 2nd gear, though. I can force it into 2nd and it just free revs up to about 4k and then kind of grabs a little bit. Can't really tell if it's going into 4th or not since I didn't drive it that far or fast. I'm guessing it's the 2-4 band? Not sure why it's throwing the 748 code. More than one issue inside this thing?

Mr. Brett

iTrader: (13)

Anybody that can chime in? I'd like to get a good idea of what I'm looking at before I go back to the builder. Could it possibly be a servo or is the band definitely shot?