p0748 / p0654 98 Trans Am

[frankmarroquin]

I have these two codes that are kicking my butt... p0654 I am guessing is cause my Tach is not working and p0748... I have replaced the pc solenoid and 3-4 clutch packs and the tranny had harsh shift now it barely wants to move front and back went it wants... Anybody have any ideas on what it could be? All help appreciated

[Tapi]

Did you find out what was wrong? After a 'write entire' 2 moths ago my rpm tach went dead and hasn't worked since. I have flashed the car about 30 times since with low speed, high speed, back to stock and back to my tune but tach is still dead. The car is '99 Vette with Z06 gauge cluster.