Charging system problem on '06 Yukon Denali

[ozman2005]

Hey guys, good to be back after a brief hiatis with a Ford. I'm glad to be back on the GM-Trucks boards with a new 2006 GMC Yukon Denali. I bought it a couple weeks ago and have a question about the charging system.

 

Since new (31 miles) when you first start the truck, either cold or hot, the battery gauge will climb to just a tad over 14 volts. Here's where it gets interesting...If the headlights are off, about 2 minutes after starting, the battery gauge will slowly drop to around 11-12 volts and remain there for the duration of the drive, whether it's 5 minutes or 2 hours. Never drops below that. Now, if it's dark and the headlights come on the gauge will remain above 14 volts and stay there as long as the headlights remain on. If you manually turn off the headlights, you can sit and watch the battery gauge drop to its usual 11-12 volts and remain there. If you turn the headlights back on, the gauge will slowly climb back over 14 and remain there, whether sitting still or driving. I've had a 2001 Tahoe and a 2004 Suburban, and in both of those vehicles the battery gauge would always climb just a tad over 14 volts and stay there, regardless of whether the headlights were on or not, so I know I'm not crazy. The truck has never been dead or sounded like it was cranking slowly, so I'm assuming the battery is being charged. I just don't want to take the chance that something could fail completely leaving me stranded or cause long-term damage to the electrical system.

 

I will take it to the dealer as soon as I have some time, but I was hoping maybe someone here might be able to give me a little insight so I can speak intelligently with the service people.

 

Thanks, and it's good to be back.

 

Oz

[GM-Tech]

Save yourself a trip to the dealer. You're probably seeing normal operation.

 

Volt Gauge Fluctuation - keywords cluster electrical excessive fluctuation gage generator intermittent IPC operation volt voltage voltmeter wire #PIT3331A - (Dec 16, 2005)

 

2005-2006 Cadillac Escalade Models

 

2005-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe

 

2005-2006 GMC Sierra, Yukon Models

 

with RVC

 

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

 

Condition/Concern:

Some customers may comment that their voltmeter is fluctuating between 12 and 14 volts on their full size pickup / utility vehicle.

 

Recommendation/Instructions:

Starting with the 2005 model year, light duty full size pickups and utilities, are equipped with a new Regulated Voltage Control (RVC) system. This system turns off the alternator when it is not required in order to improve fuel economy. The alternator will turn back on when additional voltage is required. This will cause the voltmeter to fluctuate between 12 and 14 volts as opposed to non-regulated systems which usually maintain a more consistent reading of 14 volts. This fluctuation with the RVC system is normal system operation and NO repairs should be attempted.

 

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

 

 

 

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

 

 

© Copyright General Motors Corporation. All Rights Reserved.

[ozman2005]

Interesting info, GM-Tech. I knew it had to be something more than coincidence with the headlights. Pretty cool technology, never heard of it before.

 

Thanks again,

 

Oz

[er1]

Hey guys, good to be back after a brief hiatis with a Ford.  I'm glad to be back on the GM-Trucks boards with a new 2006 GMC Yukon Denali.  I bought it a couple weeks ago and have a question about the charging system.

 

Since new (31 miles) when you first start the truck, either cold or hot, the battery gauge will climb to just a tad over 14 volts.  Here's where it gets interesting...If the headlights are off, about 2 minutes after starting, the battery gauge will slowly drop to around 11-12 volts and remain there for the duration of the drive, whether it's 5 minutes or 2 hours.  Never drops below that.  Now, if it's dark and the headlights come on the gauge will remain above 14 volts and stay there as long as the headlights remain on.  If you manually turn off the headlights, you can sit and watch the battery gauge drop to its usual 11-12 volts and remain there.  If you turn the headlights back on, the gauge will slowly climb back over 14 and remain there, whether sitting still or driving.  I've had a 2001 Tahoe and a 2004 Suburban, and in both of those vehicles the battery gauge would always climb just a tad over 14 volts and stay there, regardless of whether the headlights were on or not, so I know I'm not crazy.  The truck has never been dead or sounded like it was cranking slowly, so I'm assuming the battery is being charged.  I just don't want to take the chance that something could fail completely leaving me stranded or cause long-term damage to the electrical system.

 

I will take it to the dealer as soon as I have some time, but I was hoping maybe someone here might be able to give me a little insight so I can speak intelligently with the service people.

 

Thanks, and it's good to be back.

 

Oz

 

<{POST_SNAPBACK}>

 

 

 

 

I have 05 Silverado with the exact same thing going on. It just started doing it at 28k, and all I've ever owned is chevy trucks and they never did it so its going to the dealership and they can figure it out.

[meangoat]

OK I have a 2005 Denali... I see the charging meter moving from 12-14 but in addition to that.... all of the lights (dash, radio, headlights) move from dim to regular. This alternates each second. Whats the deal?

 

Thanks

[pm26]

OK I have a 2005 Denali... I see the charging meter moving from 12-14 but in addition to that.... all of the lights (dash, radio, headlights) move from dim to regular.  This alternates each second.  Whats the deal?

 

Thanks

 

<{POST_SNAPBACK}>

 

 

 

You could have a malfunctioning voltage regulator. most likely you need a remanufactured alternator. The GM ones are rebuilt in Mexico.