it is the senser on the top of the transmision, right below the arm that the shift cable is attached to, and is fairly easy to change.
first remove the cable from the arm, then the arm, then 2-3 bolts hold it to the trans, unbolt those, and unplug it from the computer.
make sure you remove the neg battery cable before starting anything to prevent possible computer short , then reverse the procedure for install
make sure you always remove the neg first and install it last, for electricity travels from pos to neg
if you remove the pos first and install last you can damage things
first remove the cable from the arm, then the arm, then 2-3 bolts hold it to the trans, unbolt those, and unplug it from the computer.
make sure you remove the neg battery cable before starting anything to prevent possible computer short , then reverse the procedure for install
make sure you always remove the neg first and install it last, for electricity travels from pos to neg
if you remove the pos first and install last you can damage things