I have a '03 4.8 in my chevelle and I'm using HP Tuners. My after market tach is connected to the white wire in Cavity 10 which is supposed to be the tach lead. My tach inop, can some one tell me how to change the PCM so it will work?

Also I went in and turned of all the DTC's for the stuff not being used(emissions and trans) but the MIL is still on and car not running well. I removed VATS but didn't change the actual tune of the engine. What can I do to fix this. Just need to get some things worked out so the car is drivable till I put turbos on.

 

Found the answer to my tach question on HP Tuners website. The people over there also helped me get rid of the codes too.