p0776 p2723 on new suncoast trans HELP!!

[lawson]

I recently installed a sucoast 750hp trans with billet shafts and from minute 1 it shifts extremely harsh and flares between 3-4-5-6 shifts. Pulled it back out sent it back to suncoast the say they changed pump, valve body and converter and after reinstall shifts the same. Trans has less than 200 miles on it. So far I have replaced the tcm and harness form tcm, ecm to trans (body side engine harness) with no change. Only codes are p0776 and p2723. Any ideas? I really, really dont want to take this thing out again. Thanks

 

[Mike L.]

Check voltage to trans with proper scan tool.

 

[lawson]

I checked the voltage with scan tool and it was 12.5 then I pulled on the driver side battery ground cable and the voltage dropped to 0. Thanks for getting me in the right direction. very much appreciated!