2009 Gmc Sierra

[piker50]

I hookup my laptop to my truck with the MP3 input for sound, so the kids can watch a movie on long road trips. If the battery is dead I have to plug in an DC to AC converter to charge the laptop battery. I have been doing this for a year with no trouble.

Lately when ever I plug in the DC to AC converter I get this high pitched feedback noise so loud you cant use it.

So naturally I thought it was the DC to AC converter.

So I plugged it in my Pontiac Montana SV6 - no noise it worked fine

 

So made an appointment at the dealer to get my AFM lifters replaced and to check out 2 noises.

 

They said that it was my dc to AC converter. So I went and bought a new one - no surprise it does the same thing with the new one.

 

Any ideas what could cause this? Alternator?

the noise still happens when the truck is not even running!!!!

 

on a side note - i have tried with MP3 players, my cell phone, just to make sure it was not just my laptop.