4l80E has reverse no forward gears.

robp823 · February 19, 2013

The other morning i went out to move one of our plow trucks.2004 chevy 2500hd with the 4l80e.Started it up and put it in drive and it wouldnt move.Tried manually shifting to 1st 2nd and 3rd and it would not move in any of those gears.Reverse works fine.Anyway reverse it into the garage and check the fluid.Fluid was full but smells burnt and it is black.If i rev it up high in the rpms it will start to creep.Checked for faults-none.The only thing i found looking at the data display with my solus that for the 3-2 downshift solenoid it was showing short to gnd 'yes' on the scan tool.Anyway had other things to work on so i pushed it out of the garage.That was yesterday.Today i went out to get it and now it works fine in drive.Brought it back in the shop and dropped the pan.Fluid is black.Found no broken parts in the pan just a magnet covered in about an 1/8 inch of aluminium paste.With the pan off i used the functional test and operated all the solenoids.I could hear them all click except for the 3-2 downshift solenoid.Im going to troubleshoot the solenoid issue but thats only a downshift solenoid.The description for the solenoid is just to make downshifts less harsh.Is it possible that i could have just had one of the valves sticking in the valve body.It was only 12 degreess out that morning.Any help appreciated.

Aaron · February 19, 2013

Odds are it's junk, but if the oil is black in one of those it's likely wasted.

That being said:

Double check all the electrical connectors at the speed sensor, PRNDL switch, and main harness into the trans, this sounds almost like an electrical issue to me - electrical will cause this.