4l80e stuck in first gear

[Jonathan Mantilla]

Hello everybody, I’m really stumped on this issue I’ve been having on my 4l80e, it’s a 1989 c1500 with a 5.3 ls and 4l80e, the transmission has its own stand alone harness, it was working fine for about a year until one day the transmission did not want to shift, the trans ecu is reading tps , rpm, speed perfectly fine , the transmission is not shifting , only reverse and drive works, cannot manually shift, if I power off the trans ecu the transmission will just got into limp mode and stay in 2nd gear , I’m confused what the issue could be? Any help will be appreciated

[davester]

does the stand alone controller report any error codes?

[Jonathan Mantilla]

No error codes, Everything seems to be in check , i noticed the ecu is not commanding the trans to shift just stays in 1st