Ok truxk just hit 300 miles with lq4. trans was just rebuilt last week and I'm still fighting a p1810 code( transmission fluid pressure switch) everything in trans is new and tune is dead on.. what the truck is doing is locking the converter in 25 mph and the only other thing that I haven't messed with is the spear tech harness . should i just repinn the stixk harness. anyone ever came across this problem .

 

Max out your enable temp fields for the 1870 DTC and try again? I'm just tossing it out there, the temperature based diagnostics are easiest to ignore.

If your transmission is built properly then it's most likely a tune issue.