4l80e drops out of o,d./ neutralizes. This was the original complaint remove the transmission disassemble didn't see anything obviously wrong rebuilt transmission and reinstalled, same problem.. I've replaced the solenoids. / Valve body still same problem. 1996 c 2500 5.7

Transmission needs rebuilt/replaced. Probably a 4l60E trans. if it's a 2WD---4WD could be a 4l80E. Internal damage or just worn out.

did you scan it yet,
neutral does that mean it slips.
slips means, engine RPM rises fast but not car. does it.
do not let it slip or the tranny will burnup.
the transmissions on newer cars are all electronically shifted
by the TCM brain. and it has LIMPHOME , just like engines.
and skips gears , (varies by maker what)

you need to learn or ask someone to drive car and see if problem
is engine power lost or transmission failure it takes just a short drive.

no matter what scan the PCM , see all errors and report them.
or get car serviced,
or just diagnosed (yes, put that on work order and sign it)
there 3 choices......

4L80E or 4L80? If its not an E there is a cable called a tv cable that may be out of adjustment. That will destroy a trans in a matter of few miles.

it may be your shift solenoids their are two of them that controls upshift #1 solenoid controls 1-2 gears then #2 controls 3-4 which transmission do you have in your suburban do you have the 4L60E OR 4L80E if you have an older suburban with a Carb on it then you will have the 700rr

TSSMULKEY091,

Your transmission will probly need to be rebuilt at the very least. The problem resulted from towing your vehicle and I am guessingg you didn't drop the drive shaft. Even the truck would have been in neutral the drive shaft would still be spinning a good portion of the internals of the transmission. Without the engine running, the transmission flluid pump is not circulating the fluid around the transmission and through the cooler. This will cause the fluid and clutches to burn up inside the transmission. You could try and replace the fluid and filter but I doubt it will do anything for you. I have seen this in the military numerous times. Hate to be the bearer of bad news. If you are ever in that predicament again and you can't drop the driveshaft, the rule of thumb is no more than 50 miles at 50 mph. And a lot of people say that is pushing it. Hope this helps.

Robert

4l60e or 4l80e transmission?

Sounds like the sprag or the sun gear gave up. The trans will need to come out and be rebuilt. I think amco will check it out for free and give you an estimate?

Bad transmission, that's not a good answer. Bring it to the shop [so we can guess around], not a good answer either.

A good mecahanic will respond with something about the solenoids.

I have repaired the 4L80E on my tow truck, I have to do that almost every year, the last time it ran perfectly but when I push the pedal to the metal, it shifted from 3rd gear to 2nd and stays on 2nd gear until I turn the ignition off and start again.

The transmission was totally rebuilded so the answer "Time to rebuilt the transmission" is not acceptable.

I took it back to the shop and the mechanic replaced both solenoids A and B, that was the only thing that hasnt been replaced before, it was just a guess but works

So, I am not a mechanic but my sugestion is to replace the two speed sensors and solenoids before you take the tranny out of the car and be carefull who are you taking the transmission to because guessing is not always the best course of action

The two speed sensors are easy to replace, the solenoids are inside of the valve body but you may be able to replace them without removing the transmission from the truck

Automatic trans? Sounds to me like the trans is either busted up or damaged in such a way that the gearing won't rotate or things are binding internally. With the drive shaft off, transfercase in 2WD, and trans in anything but PARK, the driveshaft should be able to turn by hand. Of, course, a drop of the pan can also give a indication. When gears bust up in a 4L80E, there is evidence.