Lights Dim on cold days

[RedLandRocket]

I have this problem and I checked the old messages and didn't see anything similar so here goes.

 

On really cold mornings, below 20 degrees, the lights seem to dim occasionally.  The dealer can't simulate the problem and above 20 degrees it doesn't happen.

[bassdog]

First off, welcome to the forum.

 

Not sure if this is the correct answer...two things, the alternator could be working a bit harder in the colder weather to make up for the strain on the battery after the truck is started (been sitting in the cold all night).

Next, again just guessing here, the gas in the lights need time to "warm up", causing the dimming.

 

Do they stay dim all day during this temp?

 

Anyone else?

 

bassdog

[RyanbabZ71]

sounds pretty normal to me

 

ANother time the lights dim is at night when your lights are on and you roll the windows down or unlock the door.  ANything that draws current will slightly take away some power which means the headlights will dim for a brief time (not long)

 

Id say your condition is normal

[chevy4x4trucks]

Mine will do something similar if the truck has been sitting out in the cold.  When I start it up instead of revving up to 1500 and dropping down to 1000 the tach will sit at 0 and slowly climb, then fall, and climb again.  At which time the lights will dim.  Don't know if that's the exact same thing as your experiencing, but if it is, just let the truck idle for a minute or so.

 

Welcome aboard.

[siume99]

Mine will do something similar if the truck has been sitting out in the cold.  When I start it up instead of revving up to 1500 and dropping down to 1000 the tach will sit at 0 and slowly climb, then fall, and climb again.  At which time the lights will dim.  Don't know if that's the exact same thing as your experiencing, but if it is, just let the truck idle for a minute or so.

 

Welcome aboard.

Howdy RedLand.  Bassdog had a good question, does it do it all day  errrrrrrr  I mean night (lights in daylight ??? ) ?  IMHO I think its just the battery getting warmed up.  At first I thought it could be the wiring, but electricity likes cold circuits better than hot.  Lights I think would warm up very quickly (seconds) from being "white hot."

 

That doesn't sound normal chevy.  Does the tach just do this or does the engine follow suit?  I doubt I can duplicate any of these situations.  Tahoes and Suburbans have a 130A alternator.  The pickups have 105 or 110s?  I really have to pay attention for my lights to dim with the door locks or the windows.  Obviously, I can see it when I want instant ventilation and lower all windows at the same time!    Neccessary sometimes when my butt falls asleep and snores  

[chevy4x4trucks]

SIUME: My truck only does that once a month or so, if that, usually following a big temp drop and the trucks been sitting out for a while.  Normally I park on the street in front of the house after work (about 3:30) and then pull the truck in the garage about 9pm.  So I think mine may be condensation on the serpentine belt.  The engine actually does it, you can feel it bog down if I put the truck in gear and try to go.  The lights dim w/ the tach so it's obvious that the engine's loosing power.

[RedLandRocket]

Thanks for the replies.

I drive to the YMCA at 5 in the morning to go swimming.  I am usually in the Y for an hour or less.  I only notice the dimming on the way to the Y, never on the return trip.

It appears to only happen on a cold morning after a cold night.  The truck stays outside all the time.  I notice that the interior and dash lights dim also but the headlights are the worst.  I haven't noticed the tach problem.  

Usually, the heater fan is turned to high and the heated seats are on and sometimes the rear window defroster

 

 

 

MyZ71

[GoFaSSter]

I have a 2000 Suburban and have the exact same problem as Chevy4X4Trucks.  It usually will only happen once during the day, but it did it to me yesterday afternoon and it had just been driven about an hour earlier.  The ambient temp. was abou 43 degrees F.

[mikeb]

The engine actually does it, you can feel it bog down if I put the truck in gear and try to go.  The lights dim w/ the tach so it's obvious that the engine's loosing power.

The engine isn't actually doing it, the battery is low and the alternator is loading up causing the engine to bog down.

[chevy4x4trucks]

I have a 2000 Suburban and have the exact same problem as Chevy4X4Trucks.  It usually will only happen once during the day, but it did it to me yesterday afternoon and it had just been driven about an hour earlier.  The ambient temp. was abou 43 degrees F.

Yeah, the temps have been changing here wildly the past few weeks, so it's been doing it more.  I think it's got something to do w/ the temp change.  I thought maybe it was condensation on the serpentine belt that may have caused it since mine goes away after about 20 seconds.

[Shaners]

 

Usually, the heater fan is turned to high and the heated seats are on and sometimes the rear window defroster

You are putting alot of draw on the electrical curcuit.  Your alternator will not make enough amperage to handle all this draw at idle speeds.  your situation is "normal".

[siume99]

Y'all have problems!    Trade your rigs in and get 2001 Chevy Tahoes, move to central IL, and park your truck outside at about a 10% incline (nose down).  That could be why mine doesn't do that, I'm at an incline. ??? Could also be because my truck was made in March (therefore newer battery) .  It sounds quirky to me.  Do you guys let your truck warm up for a couple of minutes in the morning?  I also back out of my driveway, then go into drive.  Do you guys just go to drive (when parked on the street) ?    Try putting it into reverse a few feet and then drive.  ???  IMO It's the battery age and or alternator size/age combination.

[Kansas Kid]

I doubt I can duplicate any of these situations.  Tahoes and Suburbans have a 130A alternator.  The pickups have 105 or 110s?

What would you think if I said my next pickup will have dual batteries and dual 130amp alternators?    I'm thinking its gonna take quite a bit to make much of a noticeable draw on that system....

[RedLandRocket]

My 1999 Z71 has the heavy alternator/battery but i bought it as a demo and i know it sat on the dealers lot for about 3 months.  It is 3 years old but only has 24k miles.

 

Do you think a new battery would help?

[Guest]

Mine does it also. Anytime an accessory goes on, the lights dim. I think if the General had made more branch circuits it would not happen but that would be $. Your heated seats probably suck lots of electrons away from the headlights. Anybody that goes swimming at 5 AM at below 20* doesn't need heated seats! BRRRRRR