Lights Dim when Operating Windows

[onecrazyfoo4u]

Noticed this morning on my 05 1500 5.3l. When the windows are already up, and I hold the switch up, all headlights/interior lights dim pretty bad. Voltage gauge drops below 12v pretty quickly too. Then you release the switch and all is back to normal. If I hold two window switches up at the same time, it gets even worse. Normally the voltage gauge is at 14v or so.

 

Is this signs of an alternator going bad? Is there anything I need to be concerned about? Not sure if it's the original alternator or not...currently have 145k miles on her.

[SouthernSilveradoGuy85]

How old is the battery?

[anumber1]

Agree with checking the battery.

 

Another common problem is the body ground - motor ground - battery ground loop. Its super common to need to clean corrosion from the grounds on the GMT800 trucks.

[sdeeter19555]

Mine has done this since new...if I run the windows up, the lights dim. It's because of the restrictive fuse they use to protect the charging system.

 

Sent from my SAMSUNG-SM-G900A using Tapatalk

[Coby7]

If this is different than usual just make sure nothing else has changed like maybe High beams on, HVAC full blast, rear defog because all these draw extra current. In my opinion you are probably experiencing an aging battery with extra load with changing season and I assume what you're experiencing is normal.

[onecrazyfoo4u]

Battery is from 2013, so not that old. Its been like this since I bought it a year ago. Just made me think about it today to post. It sounds like its a common thing in these trucks right, so nothing to worry about?

[Coby7]

Right, normal and all good especially at idle.

[onecrazyfoo4u]

Well it does happen when driving down the road too. Only when headlights are in though. When headlights are off, no voltage dips.

[SouthernSilveradoGuy85]

Since it does it also while driving maybe check all of the grounds. I don't know if this is a common issue for your gen, but I've never had that problem with either my '86 or my '98 and of course not my current '14. Wouldn't hurt to get the battery and alternator checked at Autozone.