Needing help w/ my 99 silverado, it has a lq4/6.0 & 4l60e trans. My Tow Haul light turns on when pressing the button, but nothing in rpms or shifting. Originally when I bought the truck, the light never came on even after replacing the wire & lever, until I changed the BCM under the steering column. Now the light turns on, but again nothing in shifting or rpms. What could it be?