1999 Durango V8 with automatic transmission (4WD) 130k miles, isn't shifting into high gear. I was told there are two sensors that may be the cause. The Check Engine light was also on when this happened. Car won't shift into high gear. Can't go faster than 40 MPH. Where are these sensors located so we can replace them? Don't want to rebuild the transmission if replacing the sensors may be the problem.