Using HP Tuners. Just got my new set up and got this error message when I tried to plug in to my 2000 Corvette FRC just now.

Reader Upload Request: x7F negative response code error

Any help would be appreciated.

Thanks.

-Ray

 

it was likely tuned with a hand-held at some point, which makes HPT go nuts, and not read the tune.

not sure what the fix is.

 

X7F negative response is as far as i can tell is either lack of voltage to the ECM or interference to the ECM from such things as the radio , body control computer (doors open and such) or aftermarket radio adapters or in my case not having the ecm totally(there are multiple pink ignition wires that need 12V) powered up on the run stand . I hope this helps someone

 

Check your battery voltage.