Headlights Dimming

[Ranger]

I have noticed the the head lights will momentarily dim only once about :10 - :15 min. after start up. I noticed this on Ruby and now again on Pearl. I will have to see if the '06 DTS loaner does it on the way home tonight. I mentioned it to the dealer and they called and said they could find nothing wrong, but someone would have to drive it home to check it out. I declined, as I suspect it is just the nature of the beast. I was at least hoping that they would say it is normal and have a TSB on it or something to explain why. Just wondering how many of you (if any) are expiriencing the same thing.

[BodybyFisher]

Only once? Ranger, let me tell you a story. About 15 years ago, I was getting heart palpitations and was worried about it. I went for a stress test and they put me on a tread mill. I was running. My heart rate was about 180 and I said there it is.... The doctor said there what is..? I said there is the palpitation. He slowed the machine down and looked at the EKG readout and said, yep I see it you are right! He said, son.... You just picked out ONE aberrant beat out of 180 beats a minute!!! Have you ever been an athlete? Um yes... Athletes are in tune with their hearts, you are paying way TOO much attention to it! If I ran 80% of my patients like I just ran YOU.... most would collapse! Once he said I was OK, the palps stopped! Whew!

The moral of the story, stop paying so much attention to what happens 10 to 15 minutes AFTER start up! Unless lights flash on your dashboard of course!

[Ranger]

Hehe, like I said, not really worried. More like inquisitive. I am pertty sure it is just the nature of the beast. What I would really like is for someone to say oh yeah, here is a TSB on it so I can print it and take it back to the dealer in the morning.

[BodybyFisher]

Just busting your chops but it sounds like its related to the TSB regarding the Deck Chairs.

[acklac7]

I have noticed the the head lights will momentarily dim only once about :10 - :15 min. after start up. I noticed this on Ruby and now again on Pearl. I will have to see if the '06 DTS loaner does it on the way home tonight. I mentioned it to the dealer and they called and said they could find nothing wrong, but someone would have to drive it home to check it out. I declined, as I suspect it is just the nature of the beast. I was at least hoping that they would say it is normal and have a TSB on it or something to explain why. Just wondering how many of you (if any) are expiriencing the same thing.

I am not experiancing the same thing..but something similar: my headlights always dim when the brakes are applied...A friend once said this is indicative of the engine "looping" (what ever that is)....Do your head lights only dim upon start up?

Only thing I can think of is maybe some other component requires addtional voltage shortly after starup...thus drawing down the availible power suppy (causing the lights to dim)?

And "long time no post" guys...lol...Still try to make it on here as much as I can...but been real busy lately....Should be on here alot more in the coming months....I got a intermittent clankity-clank coming from the engine bay...Likely a valve or a lifter..sounds like spoons tapping togeather...I should have a thread up in the next few days.

Glad to see everyone is still here...and still active

A.J.

[growe3]

You may have a bad/weak ground, and/or positive. battery cable connection.

Remove both battery cables terminals, negative cable first.

Clean the cable ends to bright metal.

Be sure to separate and thoroughly clean between the dual positive connection cable.

Make sure ground cable to engine block is clean and tight.

Make sure ground to the frame near the headlights is clean and tight.

Reconnect the battery cables, negative cable last.

-George

[JimD]

I have noticed the the head lights will momentarily dim only once about :10 - :15 min. after start up. I noticed this on Ruby and now again on Pearl. I will have to see if the '06 DTS loaner does it on the way home tonight. I mentioned it to the dealer and they called and said they could find nothing wrong, but someone would have to drive it home to check it out. I declined, as I suspect it is just the nature of the beast. I was at least hoping that they would say it is normal and have a TSB on it or something to explain why. Just wondering how many of you (if any) are expiriencing the same thing.

I am seeing the same thing on the '04 if I really pay attention and watch for it. The dimming has been reported (here, or the other board) and I am remembering it is related to the operation of the secondary air injection system pump. And I think the secondary air injection system was part of the engine changes in 2000.

I can't find the thread and my memory cells probably dismissed the issue because it is considered to be 'normal'. As the daylight hours diminish we might be hearing from other owners.

[BodybyFisher]

I have noticed the the head lights will momentarily dim only once about :10 - :15 min. after start up. I noticed this on Ruby and now again on Pearl. I will have to see if the '06 DTS loaner does it on the way home tonight. I mentioned it to the dealer and they called and said they could find nothing wrong, but someone would have to drive it home to check it out. I declined, as I suspect it is just the nature of the beast. I was at least hoping that they would say it is normal and have a TSB on it or something to explain why. Just wondering how many of you (if any) are expiriencing the same thing.

I am seeing the same thing on the '04 if I really pay attention and watch for it. The dimming has been reported (here, or the other board) and I am remembering it is related to the operation of the secondary air injection system pump. And I think the secondary air injection system was part of the engine changes in 2000.

I can't find the thread and my memory cells probably dismissed the issue because it is considered to be 'normal'. As the daylight hours diminish we might be hearing from other owners.

Now something like that makes sense. That this happens after 10 to 15 min and then only once kind of rules out most other stuff, is what went through my mind and why I was busting chops early in this thread.

[Logan]

To some extent...it is normal. One time maybe 4 miles after start up. It is the air pump. There is a service bulletin about it.

That being said. My 2001 is starting to do it once every ten miles.......time to check cables...

[BodybyFisher]

NOTICE THE 25 AMP draw of the ELECTRIC AIR PUMP. This is an interesting article as to how the charging system can operate under 1000 RPM.

Info - Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, No Start, Slow Cranking, Dim Lights at Idle, Low Generator Output #02-06-03-008A - (Jul 28, 2004)

Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, No Start, Slow Cranking, Dim Lights at Idle, Low Generator Output

1990-2005 Passenger Cars and Light Duty Trucks

2003-2005 HUMMER H2

This bulletin is being revised to add the 2004 and 2005 model years. Please discard Corporate Bulletin Number 02-06-03-008 (Section 06 -- Engine).

Any vehicle may have a low voltage display (if equipped with gauges), lights that dim at stop lights, slow cranking, no start, low generator output at idle or dim lights at idle when electrical loads are heavy at idle or under slow driving or infrequent usage conditions. These characteristics may be more noticeable with customer added electrical accessories, or with a discharged battery. These are normal operating characteristics of a vehicle electrical system and no repairs should be attempted unless a proven fault has been diagnosed.

During normal driving conditions, when engine speed is above 1000 RPM, the generator is designed to do two things:

Supply the current necessary to operate the vehicle's originally equipped electrical devices (loads).

Recharge/ maintain the battery's state of charge.

The following factors may affect generator and battery performance:

Non-usage of the vehicle for extended periods of time. The vehicle's computers, clocks and the like will cause the battery state of charge to drop (For example; 30 days in a parking lot and the vehicle may not start because of a dead battery or a vehicle which is driven only a short distance once a week may end up with a discharged battery to the point where the vehicle may not start). This would be considered abnormal usage of the vehicle and the normally expected result for the vehicle battery, generator and electrical systems.

At idle, vehicle electrical loads may exceed the low speed current (amperage) output of the generator and when this happens the shortfall comes from the battery. This will result in a drop in the electrical system voltage as the battery delivers the additional electrical current to meet the demand. This is equivalent to the brown outs experienced by homes and businesses when the electrical demand is more than the supply. See Figure 1.

Extended periods of engine idling, with high electrical loads, may result in a discharged battery. Attempting to recharge a battery by letting the engine run at idle may not be beneficial unless all electrical loads are turned "OFF".

Increased internal generator temperatures from extended idling can also contribute to lower electrical system voltage. As the generator's internal temperature rises, the generator's output capability is reduced due to increased electrical resistance.

The following are some typical examples of electrical loads:

System Amperage Load

Rear Window defogger

25

Electric AIR Pump

25

Heated Seats

5 Amps per seat

Headlamps (high)

20

Blower Motor (High)

20

Headlamps (low)

15

Brake Lights

6

Windshield Wipers

6

Ignition

6

[Regis]

My lights will momentarily dim when I turn on the AC and the blowers jump to High. Once the system is on it never repeats itself. I've noticed this ever since I can remember.

[Ranger]

Do your head lights only dim upon start up?

No, this does not happen at start up. Only as mentioned :10 min or so into the trip and a few miles down the road. Coming home from work (at night) it usually happens after I am on the toll road at 70 mph and with RPM at 1950. Maybe that is when the air pump kicks in. I am about to go pick her up and will ask a mechanic about the timing of the air pump operation.

[JimD]

One other little tidbit regarding electrical loads; the secondary air pump and the ABS systems both run off 50 ampere fuses.

In terms of OEM factory installed equipment, a circuit fused at 50 amperes is a substantial load.

[Ranger]

Well, got Pearl back and she is glad to be home. They did deface her though. I had to remove the dealer licence plate frames that they always install . Never did get to talk to a mechanic. George Bush should be so well protected. I am quite sure that the momentary dimming is normal and will not worry about it.

[BodybyFisher]

Lucky it wasn't the stickers on the body. What guts to put the frames on however, its amazing. Maybe next time I go to the service department I'll force the Service Writer to wear a shirt with the name of MY company on it! I need some free advertising too.

[KHE]

Well, got Pearl back and she is glad to be home. They did deface her though. I had to remove the dealer licence plate frames that they always install .

Geeze.... I can see putting one of those cheesy frames on their cars when they sell them but to do that on cars that come in for service takes gall.

Maybe next time I go to the service department I'll force the Service Writer to wear a shirt with the name of MY company on it! I need some free advertising too.

[Ranger]

I probably should have made someone come out and remove them (next time I will). However they always call to ask if I was happy with the sevice. They will hear about it.

[Bill K]

My youngest son is in the Navy so I have a Navy L.P. frame. The dealer hasent messed with it.

Put on a nice frame and they will probably leave it alone.

[Ranger]

Yeah, that is probably the trick. I don't have any frames nor really want any on it.

[BodybyFisher]

I need a new one of these, the sun and elements faded my old one.