4l80e tranny wont move

bigs10blazer · Jan 23, 2015

ok ,,99 silverado 5.3, my sons truck,(16)), we put a cam and exhaust in the engine,,, wow runs great,,, 4l60e didnt last very long, my son found a deal on a 4l80e out of a 01 silverado, with flexplate and spacer plate,
we reserched as much as we could, there are some great websites out there for help, thank you !,
so we repinned the plug on tranny and at the ecm in the engine compartment, tranny wont move, we added 12quarts of oil, i assume the pump is working if it sucked down the fluid. the shifter on the dash shows the different gears it went in, reverse and drive,
we used the neutral switch from the 4l60, i know we need to tune the computer for the 4l80 but the guy says it should go into reverse and second gear with out tuning it.
when you start it up and put in reverse and drive the drive shaft changes direction, but wont try to move. is tranny just bad ? kid we got it from swears he drove truck , (he got the the 6.0 ) or is still in the tunning part that wont let it move , we unpluged big plug on tranny and it still wont move, someone said to try that,

LightBnDr · Jan 23, 2015

Hydraulically with the plug removed it will go into reverse and 2-3rd in D depending on year.

First thing is make sure tcase is not in neutral

Second is pull the pan and make sure manual valve is hooked up to the linkage. If its not, that's a red flag someone has been inside recently. Then it's a crap shoot as to how long it will last.

Post up. I wanna know

bigs10blazer · Jan 23, 2015

I assume transfer case is working it does switch from two high four hi and 4 lo and the drive shaft does try to turn from reverse to drive when you switch the gears. And you can here tcase motor switching gears.in the air ,in gear tires do not move and tires rotate by hand like its in neutral.
Can i check pump pressure at the tranny line with a fuel pump gauge?

LightBnDr · Jan 23, 2015

Not really with a fuel pressure gauge. Most don't go high enough and the adapters won't fit the line pressure tap. Sure you could make something work. If its at least 190psi it's gonna move

Plus if you're using an auto tcase like you say, the encoder motors had problems all the time. Plus you have to wire up a tcase control module with the tcase mode switch for all of this to work right anyway.

I personally would pull the encoder motor off the tcase and shift it by hand with a small wrench. That will rule out the tcase 100%

The encoder motors can clunk and bang, makin you think it's shifting but it can default right back to neutral.

bigs10blazer · Jan 23, 2015

We used the transfer case that was in the truck and it was working great before. We just change the input shaft on the transfer case and bolted it up to the 4l80e

bigs10blazer · Jan 23, 2015

but we can double check also

LightBnDr · Jan 23, 2015

Keep it basic and simple. Don't grasp for straws.

You runnin a 246 tcase?

KILLERB468 · Jan 23, 2015

like mentioned pull the pan and see if the manual linkage is hooked up...but also make sure there is a filter in it when you pull the pan. No filter no move and will take fluid. You got 12 quarts in it? does it register on the stick or way up the dip stick?If it is way up the dip stick the trans isnt pumping fluid. you should get right around 14 quarts in it if the trans and converter were empty, but if a used conveter and trans 12 should be on the money.

LightBnDr · Jan 24, 2015

Any updates?

bigs10blazer · Jan 25, 2015

we put new filter in when we put the tranny in,, so that not it ,
what we did today was pulled a tranny cooler line off, started up,, no fluid is coming out :dunno:

in gear and in park and in neutral,,, nothing

LightBnDr · Jan 26, 2015

I have seen sometimes people stab a Trans and not have the converter fully seated in the pump. After tightening all the bell housing bolts it forces the converter nose into the pump gear ears and snaps em right off the drive gear.

You crank it up and the pump isn't turning. I'd be looking at that next

bigs10blazer · Jan 26, 2015

transmission and converter are installed correctly that is not the problem

bigs10blazer · Jan 26, 2015

Shouldnt the pump work or flow transmission fluid through the lines even if the manual lever is not hooked up inside somehow?

LightBnDr · Jan 26, 2015

Yeah no matter what gear range, the pump is always gonna have cooler flow. If you got nothing out the cooler or line pressure plug, you have a pump problem.

Even if the converter is destroyed, you will have fluid flow at idle at both of those.

bigs10blazer · Jan 27, 2015

i was figuring the pump or a bad converter from the start,, but just was hoping it was something else,

Hucklebuggy · Jan 28, 2015

It's a long shot, but you might check the fittings for the cooler lines that screw into the transmission. One is longer than the other. Can't remember which one is pressure or return, but if the the long one got bottomed out in the short hole, and that was the pressure side, you get no flow from lines... ... no idea if that affect function or not. One of these other guys probably knows though.

bigs10blazer · Jan 29, 2015

the rear line is the long fitting that goes deep into the tranny, not sure why the guy before us removed it, but we did have to buy it new, the cooler lines were flushed out with tranny line cleaner and air blown through,

LightBnDr · Jan 29, 2015

So still no fix yet? You didn't throw a pressure gauge on the line pressure plug?

Shake n bake, I wanna see some pics

bigs10blazer · Jan 31, 2015

pulling tranny on sunday,, to see if linkage inside is not hooked up or wrong torque converter or what other bs

LightBnDr · Jan 31, 2015

4L80s are great transmissions. I have always liked them. Though they are a Trans that requires a bit of precision when building them. In my experience, if there is a small issue with pressure loss, they will burn to the ground in just a drive around the block. When they are built right and crisp, they will handle alot of abuse and run for a long time.

I hope it goes smooth for you. Interested in what you find