rhythmic scratching sound in Trailblazer
This is a weird one regarding my wife's 2002 Trailblazer. She has heard it on and off for weeks and I finally happened to catch the noise.
It is a rhythmic scratching sound about 2 times per second coming from under the driver's side dash. Kind of a "ch ch ch ch" sound. The sound repetition stays the same speed regardless of engine speed. The sound comes and goes; usually, if the truck is restarted, the sound goes away.
Weirdest thing: If I turn the lights on, the noise stops for a second, then restarts. I suspect the drain on the electrical system stops whatever is causing the noise temporarily.
Any ideas what's going on?