lights surging?

[mykon04]

it is a 2004 gmc yukon with 5.3 and 230000 miles I just recently noticed the lights kind of surging while sitting in one spot and idiling. stock stereo and no other mods than a few leds in floor pans and overhead lights.

My first thought was the voltage regulator on the alternator so whipped into auto parts store and bought new alternator and installed; the problem is still there. I currently have a yellow top optima battery thats 2 years old and it checked out fine also.

Could this be a loose ground issue?

Any help you can give would be awesome, Thanks.

 

[Donnie Yukonie]

Do you have the A/C on while this is happening?
I know on my 98 when the compressor Cycles I can see a Slight Dimming of the headlights
I.e when it cuts on and off .

Have you had the truck Tested at Idle for Voltage Dips and jumps?

 

[YukonXLPerk]

I had an 06 tahoe that did this when the AC or the fan would kick on.
I have heard that you can fix this by doing a "big 3" conversion, but have not tried this myself.

 

[johninsc]

Mine does the same thing more like pulsing on all lights. I need to try the big 3.

 

[ccapehartusarmyINF.(ret)]

check all your terminals grounds everything its possible youve got high resitance somewhere do you know how to use a muti meter?

 

[mykon04]

Thanks

Well for some reason my email notification went to spam.

But thanks for the good info.
I will check the grounding leads.

it does it like a constant pulse I believe with the A/C on or not. I understand when the compressor kicks on it will draw amperage to run as well as drag down the engine some. that would be just a one time flicker and then back up this is a soft pulse. Not a huge issue but it is bugging the shit out of me. Especially since i bought the 150 dollar alternator!

I will clean the grounds and check again when I get back home next week. and update everybody then.