I just purchased a 97 LSC, and I love it. But just recently I noticed that the whole wiper system is going crazy. The wipers turn on when I turn the knob to low, int, and high but the motor is loud as hell! Is that normal? In addition, the wipers will not turn off once turned on. I slide the knob back to off, but they still continue to run for several minutes before they decide to turn off...anyone out there got any answers? Pls reply.