Hi All!
I have a 2000 Sierra with a new noise that I am having trouble locating & wonder if you all don't mind lending your expertise.
When the truck is moving slowly I hear a rhythmic chirp - chirp - chirp. I don't know if the noise continues at normal driving speeds because of ambient noise overriding the chirps. I tried driving between some buildings for the reflected noise, but no luck hearing the chirping past low speeds.

A Clue: It only happens when the truck is in gear. When the truck is moving and I put it in neutral, the noise stops. This makes me eliminate the wheel bearings & brake wear sensors. (I did look at the brake pads. They are thick and the sensors are far away from the rotors.)

I was instantly concerned about the transmission. I checked & the fluid is good looking, good smelling & at the proper level. I had the transmission fluid, both differentials and the transfer case fluids changed 15,000 miles ago. The transfer case output shaft seal was replaced 2,0000 miles ago.

Do you folks have an idea of what I can check next or suspicions about the source of the noise?

Thanks Very Much for your thoughts!
Paul

 

Does it do it in reverse?

 

Thank You for taking time to reply TMW. I appreciate it!

Being the Bird Doo Head that i am, I forgot to check reverse. I just checked it against a 1/4 mile long factory wall and it does make the sound in reverse but...
It is not nearly as loud and it is not consistent. In forward, it is chirping 100% of the time and in reverse I could have many feet of silence, then the noise. If it m going in reverse and put the shifter in neutral, the noise also stops, like it does in forward.

Thanks Again for helping. This one has me quite stumped.
Paul

 

I suggest you take it to a transmission shop, someone you trust or a good friend may be able to recommend.

 

Thanks Again, TMW
I was afraid that would be the necessity. Hopefully it's nothing too costly (yeah, sure....)