I noticed when I start my truck at night my lights will dim a few times after running for a sec as if something is drawing a lot of amps. AC/def is turned off. Truck will be sitting there running in park with the doors open which is how I noticed it when I was standing outside of it.

What's running that would cause this? Just a mystery I'd like to figure out

 

Yes, it is the grid heater recycling, search for "lights dimming" for more information. The Search function is your friend! Merry Christmas and congrats on new truck!

 

Its just the grid heater turning on and off since it is colder.

 

Someone's stealing yo powah! Check exterior for cables.

 

There is a "Stickey" on this subject which means a lot of people have asked. COngrats on the new truck!

 

Hahaha, yeah I agree should have searched this. I envisioned a weird short out in my truck though.

Glad to know I'm ok, thanks!

 

I KNEW IT!!! Darn those elves!

 

Does it make a bang/thump type noise when the needle drops and then again when it comes back up? Mine does.

 

That's the AC you're hearing.

 

Who wouldn't.... with their pointy ears, evil smile and devilish beards.

 

Sorry to hijack, but it is? It isn't turned on, nor is my defrost or anything else.

Why does it only do it randomly. Like while they are cycling it may only do it once, or not at all? Engine surges as well.

 

I don't care if you hijack now...

Is it a loud bump/thump? That I always thought was the A/C but it has to be on. I now turn mine off everytime I shut the truck off so I don't get that right after cranking the truck up again.
FWIW, my 04 did that since almost new and as far as I know the guy who bought it from me hasn't had a problem out of it.



There is also a quiet thump... I get it when it's cold out it seems after first cranking it. I think it has to do with as mentioned above the grid heater which is causing the amp drain on my system that had me worried. Anyone can correct me if I'm wrong.

 

Mine has the little thump as well that you are talking about. I think it's from the grid heater turning on with such a large amp draw. I know for certain it's not the a/c because I listened for it and watched my amp gauge and right when you hear the noise the gauge drops drastically and the lights dim. Besides why would your a/c compressor come on if it's turned off!!

 

Yup Gig'em Class of 05 here. What are you majoring in?

 

We need that Sticky in this forum, seems most of the inquiries show up here.