I am tuning a LS conversion for a friend. its a 2003 burb 5.3 with a 4l80e added.
The TC locks up as soon as you get into 2nd gear. Even though I have the 2nd gear table set to 255 and even tried 128 mph in case 255 was invalid.
The only way I stopped it was setting the PWM duty cycle to all 0's. I tried copying the trans tables from my malibu cause that only locks up in 4th but it did not help.
PCM is a P59 with 12579405 OS which appears to be ok for 8100 motors with a 4l80e so I cannot imaging the OS being the issue.
The lockup will not release till we almost completely stop and the motor almost stalls. If I inhibit the TCC in HPtuner (VCM scanner) it will obey and stay off.
I am trying to attach the tune. I seem to be doing it wrong. stand by.
do you have any scanner runs? when he installed the 4l80e did he update the wiring for the 2nd speed sensor? Im assuming you did a segment swap for the 4l80e trans?