I have a 2002 F250 7.3L with 170k miles. It has a bullydog outlook display unit, but the truck throws a check engine light and an airbag light code. It was wrecked when I bought it and now it is fixed, but when I try to read the codes with my Matco OBD2 reader the codes do not read and the truck starts to stutter and almost shut off.
I have a feeling that the display unit has a tune on it (revving the truck blows black smoke so its not the stock tune) and that is blocking the matco reader from reading the codes. But I don't have any clue about the tuner or how it complies with the reader. Has anyone had an issue like this? And how do I clear the codes if the reader wont connect or read the codes.
NOTE: Taking off the battery cables do not clear the codes.