need some help pls
5.3 4l80e swap not shifting feels like limp mode stuck in i wouold say 2nd gear but does not cap rpm.
engine runs fine just no shifting
psi standalone harness
tried manually changing gears & nothing
fluid shows filled
checked power to end of harness, good
checked ohms at trans everything is in spec, good
no codes popping up on scanner
unplugged trans connector and drives the same
grounds are clean and id imagine if it was ground issue engine wouldn't run its a standalone harness grounds ran together
scanner shows speedo working so i would assume vss wiring/sensor is fine

bad pcm?
bad solenoids?

don't have bidirectional scanner to test solenoids by ear but if ohms checked out would that be sufficient?
trans plg did have some fluid but ohms checked out would that also be sufficient in troubleshooting?

any help or ideas would be great, thanks in advance

 

if it's not electrical (which is what an only "2nd and reverse" situation usually is,) mechanically I'd look at the low roller clutch.

 

You didn't mention what PCM you had controlling all of this and depending on who set up your PCM it could be possible they didn't load a 4l80e tune and it's still a 4l60e. I know you said no codes but it is possible they don't have DTCs being triggered for trans errors. I'd have to say you can't count out a harness/wiring/pcm issue until you can get in there and look at that tune. I've had a few people have similar issues and this turned out to be the cause.