Headlights dim/electrical draw?

[Brandon2489]

Vehicle info. 2011 Tahoe LS 4x4. Bought with 80k and now has 136k.

On to the concern. For the 4 years I have had the tahoe I have always noticed the headlights would randomly dim while driving at night. Tonight I realized they dim when the electric fans kick on. I also noticed the voltage gauge was reading around 12 volts and the headlights seemed dim. After about 5 miles or so the voltage was back to 14 volts and headlights seemed brighter. This may be my eyes playing tricks on me as well. I should note I usually don't look at the volt gauge often. So I can't say if it normally does this or not. Has anyone else noticed this with the headlights? I will be honest and say I am pushing my luck on my battery. I have never replaced the battery and I do not know the last time it was done. The date is no longer legible on the sticker. Although I do not think it is a battery issue at the moment.

 

[RedInCo]

12 volts is low.

On my 2010, when you turn on tow/haul mode, the voltage holds at a higher level than normal. That is so it does a better job of providing power to a travel trailer. You could try tow/haul mode and see if that gives you brighter lights/higher voltage.

 

[Doubeleive]

my fix would be:
new battery, ground headlight harness to frame on each side.
oh ya, that is my fix, lol that and some nice hid's, they don't dim.

 

[Brandon2489]

my fix would be:
new battery, ground headlight harness to frame on each side.
oh ya, that is my fix, lol that and some nice hid's, they don't dim.

Thanks for the advice. Question for you? Are you using projectors with you hid's or just the hid's in stock reflector?

 

[Joseph Garcia]

These trucks have internals that reduce the draw on the alternator, when not needed, so you will see some occasional fluctuations on voltage on the gauge, bringing it below 14 volts. That is normal.

I do not believe that your light dimming issue is directly associated with the changes in voltage that you are seeing on the gauge. As suggested above, replace your battery and clean up any electrical connections associated with the battery/alternator/ground circuit. Once your battery is replaced and all primary wire and ground connections are clean and tight, if the dimming issue still exists, then we can further troubleshoot with you.

 

[Doubeleive]

Thanks for the advice. Question for you? Are you using projectors with you hid's or just the hid's in stock reflector?

hid's in the stock housing, some guys do the whole bake them in the oven and install projector thing but not my cup of tea so too say.

 

[Doubeleive]

if you go hid do it right with a couple relays and wired to the battery and it will work great, the stock wiring isn't really hid friendly

 

[CaptainAmerica1]

The way the light sensor works will wear hids out with all the flickering at vehicle startup, I wired in a 10 second timer to my light sensor so they come on after the truck is already started.

 

[petethepug]

You’re due for new battery cables. It’s can be considered a maintenance item after 100k mi. The dimming effect is the BCM (ECM) tied into the entire system that works as a regulator.

The new cables will help to eliminate the draw down you’re experiencing. A HID kit is the way to go in the future for adequate lighting. As others have stated make sure you relay the HID to the stock switch. That flickering on start up can wreak havoc on other systems and is a side effect of inadequate voltage or ground on start up. The relay will help isolate the HID igniter from the system.

 

[avalonandl]

I installed Sealight LED bulbs, they work well. Not as bright as HID but doesnt draw as much juice.

 

[CaptainAmerica1]

Same

 

[Brandon2489]

You’re due for new battery cables. It’s can be considered a maintenance item after 100k mi. The dimming effect is the BCM (ECM) tied into the entire system that works as a regulator.

The new cables will help to eliminate the draw down you’re experiencing. A HID kit is the way to go in the future for adequate lighting. As others have stated make sure you relay the HID to the stock switch. That flickering on start up can wreak havoc on other systems and is a side effect of inadequate voltage or ground on start up. The relay will help isolate the HID igniter from the system.

Should I do the big 3 upgrade or just replace the cables with oem parts.

 

[petethepug]

I always take advantage of upgrades at maintenance time. This one I’d go with the best bang for the buck unless you’re planning some upgrades.

 

[iamdub]

Vehicle info. 2011 Tahoe LS 4x4. Bought with 80k and now has 136k.

On to the concern. For the 4 years I have had the tahoe I have always noticed the headlights would randomly dim while driving at night. Tonight I realized they dim when the electric fans kick on. I also noticed the voltage gauge was reading around 12 volts and the headlights seemed dim. After about 5 miles or so the voltage was back to 14 volts and headlights seemed brighter. This may be my eyes playing tricks on me as well. I should note I usually don't look at the volt gauge often. So I can't say if it normally does this or not. Has anyone else noticed this with the headlights? I will be honest and say I am pushing my luck on my battery. I have never replaced the battery and I do not know the last time it was done. The date is no longer legible on the sticker. Although I do not think it is a battery issue at the moment.

As @Joseph Garcia mentioned, this may just be the RVC (Regulated Voltage Control) functioning.

Still, GM, if not most all auto manufacturers, are known for having the wiring in their electrical systems to be marginally adequate at best. You could disable the RVC function by unplugging the sensor on the negative battery cable and see if the dimming goes away. If not, then you have charging and/or battery and/or ground problem(s). I'd still recommend a Big 3 upgrade or at least inspect and clean all the factory grounds.

 

[swathdiver]

Vehicle info. 2011 Tahoe LS 4x4. Bought with 80k and now has 136k.

On to the concern. For the 4 years I have had the tahoe I have always noticed the headlights would randomly dim while driving at night. Tonight I realized they dim when the electric fans kick on. I also noticed the voltage gauge was reading around 12 volts and the headlights seemed dim. After about 5 miles or so the voltage was back to 14 volts and headlights seemed brighter. This may be my eyes playing tricks on me as well. I should note I usually don't look at the volt gauge often. So I can't say if it normally does this or not. Has anyone else noticed this with the headlights? I will be honest and say I am pushing my luck on my battery. I have never replaced the battery and I do not know the last time it was done. The date is no longer legible on the sticker. Although I do not think it is a battery issue at the moment.

It's probably the battery, just plumb wore out. Look up RVC (Regulated Voltage Control) and EPM to learn about the charging system on your truck. AGM batteries like fast charging and the system in these 900s is not designed to work with them. They don't last as long as they should, GM does not recommend them for our vehicles, stick with traditional lead/acid batteries. My ACDelco's have served me well here in Florida's heat.

 

[Brandon2489]

I always take advantage of upgrades at maintenance time. This one I’d go with the best bang for the buck unless you’re planning some upgrades.

No upgrades

It's probably the battery, just plumb wore out. Look up RVC (Regulated Voltage Control) and EPM to learn about the charging system on your truck. AGM batteries like fast charging and the system in these 900s is not designed to work with them. They don't last as long as they should, GM does not recommend them for our vehicles, stick with traditional lead/acid batteries. My ACDelco's have served me well here in Florida's heat.

Yeah I was planning on sticking with the lead acid battery style that it is currently using. I will say this vehicle is finicky with electrical. In the past on other vehicles I have never had these issues with headlights dimming while driving due to a bad battery. The only sign of a bad battery on other vehicles is when it just plain old won't start haha. Like I said this has happened for the past 3 years at least and it has gone through hot summers 95 plus and cold winters 10 degrees and up and has never skipped a beat but headlights have always done this. I will replace the battery for insurance though. Thanks for the help

 

[swathdiver]

No upgrades

Yeah I was planning on sticking with the lead acid battery style that it is currently using. I will say this vehicle is finicky with electrical. In the past on other vehicles I have never had these issues with headlights dimming while driving due to a bad battery. The only sign of a bad battery on other vehicles is when it just plain old won't start haha. Like I said this has happened for the past 3 years at least and it has gone through hot summers 95 plus and cold winters 10 degrees and up and has never skipped a beat but headlights have always done this. I will replace the battery for insurance though. Thanks for the help

Yeah, the system is like a smart charger, it'll keep a weak battery going for a long time. Our first vehicle with RVC and EPM would flicker the lights a lot and that started about a year or two before the battery died. Same for my truck. You can unplug it and have the alternator run at full output, it's right off the negative terminal.