The other day my grid heater kicked on before I started my truck and it made a strange high-pitched squeal. The squeal quit after the heater went off and hasn't done it since. Any ideas what that was?

 

Mine does it too when it gets cold like 10 degrees or colder

 

I think this is a common event as my truck does it to from time to time.
As to the why? I can only guess that it may not be the grid heater, but rather the heater solenoid, or perhaps maybe the voltage regulator on the alternator, I really dont know.

Rich.

 

I haven't heard it on my truck, many heaters in machines make strange noises when they warm up. I think it's kinda like when you've been out hunting all weekend and you get up Monday to go to work. You stretch and yawn and make all kinds of ooohhha, aahh, oowww sounds.