alex_fiege

Hey, just got a 2007 Tahoe LTZ. Seems that at idle I have a slight engine rumble, I'm thinking it needs a tune-up, 96,000mi. What concerns me is that when it is idling my headlamps and dash lights flicker, and if the door is open, the dome too. Charges at 14v or above on gauge, doesn't matter what accessories are on or off, doesn't matter if it's in gear or not, and it doesn't do it at any range but idle.

My first guess would be a voltage regulator or a grounding issue, but if these are like the cars I fix for a living, there is some kind of battery control module which has an influence over the charge rate. Just wondering if anyone has seen this issue before. I seem to remember having seen it on some of the older Chevy trucks, but have never actually had to deal with it personally.

Anyhow, I'll do a tune-up for sure and see if that helps the rumble, and wait until I can get it into the shop next week to go further into the lights. Let me know if you have prior experience with this problem.

Thanks,
Alex

73shark

Welcome to the forum.

The computer controls the alternator output voltage on the new models. The flicker might be caused by a bad ground somewhere.

alex_fiege

Thanks, that was kind of my thought. It seemed worse tonight, I think I may have seen the battery light come on for a second or two at a stop light. Also looked like it might be happening off idle now too, but hard to tell. Maybe I'll try to look into it in the morning.

in2pro

If the battery is more then a couple of years old I would suggest replacing it now before it leaves you stranded...the new body style and at least the 07 models tend to go through batteries... they are too small for the demands placed on it....I think I am on battery number 4 in my 07....

titantn24

I installed an additional battery last year for that reason on my 07 Burb LTZ. The tray is there, might as well use it. Serves as a backup if the primary battery fails to start the engine. Great peace of mind.

alex_fiege

Thanks for all the tips. Got in this morning to take a relatively long trip and within a couple of blocks my charge voltage dropped to about 11.9V. Battery checked out fine on digital tester as well as with meter, 12.4V standing, 10.3V cranking. Went home and checked with a meter and found at idle that voltage at the battery was fluctuating rapidly, as much as 1V within 5 seconds. Replaced the alternator and cleaned all the connections at the battery, main engine ground, and main battery fuse and problem solved. Charge voltage stays up, and when I had it out tonight the lights were all nice and bright with no flickering.

titantn24, I see the tray at the left front of the engine compartment, are the cables also in place or do I need to order them. I'd like to do that mod for the cold Minnesota winters...

titantn24

You'll need this: http://www.painlesswiring.com/webcat...rchField=40120 it includes the cables you'll need. You'll need some marine type battery terminals too. My wife took the Burb to work this AM, but I can take some pics of my setup this evening if you like.