Lately, when I start the Z, there is a high pitch whining noise. I took the Z to the shop and they thought it was the belts and or alternator. Had the belts replaced on Tuesday and mechanic said he would let me know if he thought the alternator would need replacement. Never heard back about the alternator. The sound didn't come back until this evening when I left work. It lasted about 15 seconds and I accidentally tapped the shift **** (automatic trans) and the sound went away. I haven't noticed and problems during gear shifts or any transmission problems. Could it be the transmission or should I have him check the alternator or pulleys again?

 

I too had this problem and still do. But the whining was very loud right before my tranny blew. I got a new one and theres still some whining im curious to see what this is

 

The whining noise on my Silverado went away when I had the tensioner pulley on the AC belt replaced.

 

yup what it sounds like to me.