headlights dimming when braking ? [Archive] - GrandAmGT.com Forum

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kipper1012
03-29-2008, 08:42 AM
well I have had it with my headlights ever since I bought my GA when I hit my brakes at night my headlights dimm for like a split second. and everyone thimks I'm flashing my highbeams at them. has anyone else had this problem?I did a search and found nothing .
thanks

Graxall
03-29-2008, 08:44 AM
well I have had it with my headlights ever since I bought my GA when I hit my brakes at night my headlights dimm for like a split second. and everyone thimks I'm flashing my highbeams at them. has anyone else had this problem?I did a search and found nothing .
thanks

Battery
Alternator?

kipper1012
03-29-2008, 09:00 AM
new battery (2 months ago) new Alternator (8 months ago) this has been going on for 4 years ever since I bought it.

Graxall
03-29-2008, 09:16 AM
new battery (2 months ago) new Alternator (8 months ago) this has been going on for 4 years ever since I bought it.

Then its your wires prolly.. Throw a volt meter on the wires and see whats going on..Sounds like some sort of power leak...

kipper1012
03-29-2008, 09:23 AM
what am I looking for on the volt meter? elec was not my strong suit

Graxall
03-29-2008, 12:34 PM
what am I looking for on the volt meter? elec was not my strong suit

Mine either

http://www.ehow.com/how_16767_voltmeter.html

basically, depending on what kind you have, you will plug each point of the meter on/in the headlight hardness and read the voltage comming out...Idk exactly what the voltage of stock headlights should be pushing..someone on here might.

cardude007617
03-29-2008, 06:13 PM
check your vehicle grounds, if theyre dirty and corroded, clean em!

Kyle
03-29-2008, 06:27 PM
Make sure the battery conections are tight.

andrewe77
03-30-2008, 07:12 PM
Mine has done it since it was new. I think it's normal.

cardude007617
03-30-2008, 07:23 PM
i doubt its normal. check the contacts for the positive on your fuse box (that bolt), mine at one time was corroded and i cleaned it up and it helped a bit

Black_GAGT
03-30-2008, 08:58 PM
mines always done it to.

Malaclypse
03-30-2008, 09:44 PM
If the vehicle has done it since it was new, I'd say its normal operation if there are no other ill effects. Its just the PCM and alternator playing catchup with the voltage draw of the vehicle systems.

Here's a bulletin that's pretty much to that effect. The important bit is towards the bottom in bold.

#02-06-03-008C: Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, No Start, Slow Cranking, Dim Lights at Idle, Low Generator Output - (May 30, 2007)


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


Models: 1990-2008 Passenger Cars and Light Duty Trucks (including Saturn)

2003-2008 HUMMER H2, H3

2005-2008 Saab 9-7X




--------------------------------------------------------------------------------

This bulletin is being revised to add the 2008 model year. Please discard Corporate Bulletin Number 02-06-03-008B (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





Depending on the vehicle application, generator current (amperage) output at engine idle speeds of 600-700 RPM can be as low as 35 percent of the full rated output. With enough electrical loads "ON", it is easy to exceed the generator current (amperage) output when the engine is at an idle of 600-700 RPM. This is a normal condition. The battery supplements for short periods of time. Items that affect the vehicle's electrical system current and voltage at idle are the number of electrical loads being used, including add-on accessories, and extended idle times. When the vehicle speed is above approximately 24 km/h (15 mph), the engine/generator RPM is high enough and the generator current (amperage ) output is sufficient to supply the current (amperage) requirements of the vehicle as originally equipped and recharge the battery.

Dimming lights at idle may be considered normal for two reasons:

As the engine/generator speed changes, so will the current (amperage) output of the generator. As a vehicle slows, engine/generator RPM slows, and the current (amperage) output of the generator may not be sufficient to supply the loads, the vehicle system voltage will drop and the lights will dim. Dimming of the lights is an indication that current is being pulled from the battery. If the battery is in a low state-of-charge (discharged condition), the driver will notice a more pronounced dimming than a vehicle with a fully charged battery.
When high current loads (blower, rear defogger, headlamps, cooling fan, heated seats, power seats, electric "AIR" pump, or power windows) are operating or cycled "ON", the generator's voltage regulator can delay the rise in output. This effect, usually at lower engine speeds, can take up to ten seconds to ramp up the generator output. This is done to avoid loading the engine severely. To increase current (amperage) output, additional torque is consumed by the generator. The engine computer (PCM) will ramp up engine/generator speed in small steps so engine speed variations are not noticeable to the driver.
For diagnosis of the battery and or the generator, refer to the appropriate Service Information or Corporate Bulletin Number 05-06-03-002B.

kipper1012
03-31-2008, 06:44 AM
so this is normal acording to this TSB. but if I put in a high output alternator that would correct the issue right?

350rs
03-31-2008, 07:10 AM
could. but putting too much power to bulbs in particular can cause premature failure. Unless you somehow adjusted the voltage regulator in the alternator you cold end up doing this among other possible things. Ive never had an OBD-2 car and their systems are much different than OBD-1 or older cars ( NO OBD at all). But i know this is true about my old camaro so i thought i would share my knowledge for what i know of it

cardude007617
03-31-2008, 01:56 PM
no, the bulbs will only consume as much power as they need to.

Malaclypse
03-31-2008, 07:14 PM
could. but putting too much power to bulbs in particular can cause premature failure. Unless you somehow adjusted the voltage regulator in the alternator you cold end up doing this among other possible things. Ive never had an OBD-2 car and their systems are much different than OBD-1 or older cars ( NO OBD at all). But i know this is true about my old camaro so i thought i would share my knowledge for what i know of it

no, the bulbs will only consume as much power as they need to.

Bulbs can actually have a shorter lifespan if the voltage of the system is increased. It'd mean more heat for the filament to dissapate during normal operation. However, most HO alternators concentrate on the amperage because that's what is usually needed.

That being said, a HO alternator would not fix the issue as the PCM still commands a certain amount of output from the alternator. When a high amperage accessory is turned on you'd still have the initial sag in system voltage.

kipper1012
03-31-2008, 07:36 PM
so there is no real fix than just deal with it?

Graxall
03-31-2008, 07:52 PM
so there is no real fix than just deal with it?

Have you tried replacing the bulbs? THey could be bad as well...Or just getting HID's will fix this...Because HID's run on even less power than the stock bulbs...The ballasts provide them with power, well the headlight harness goes into ballast, ballast sends only nessecary power to the bulbs...soo....yea

kipper1012
04-01-2008, 02:26 PM
yea i'm looking into hid's

intmd8r
04-24-2008, 02:06 PM
Hmmmm. That's disapointing news from the TSB. My '03 GAGT has had the dimming light syndrome since I bought it. Every GA that I have ridden in, regarless of the year or condition has had the same symtoms. I'm wondering if installing a voltage regulator would cure it? There are some cheap ones for sale on e-bay right now.

BTW sorry for bringing this post back from the dead, but it is an issue that's driving me insane.

stillriza
04-24-2008, 02:58 PM
ya mine does it too since i bought it. I also noticed when i was in an o3 caravan with no system or any extra electronics installed..it does the same thing.

no biggie

silverbullet51
02-28-2009, 08:20 PM
I've got the same problem, especially noticeable when blower is on high and rear defroster is on. I thought my alt was going bad so I went to Autozone and had it tested- they said my alt was good. After reading that TSB, I apparently have nothing to worry about since this is a normal operating condition. There is too much of a load at idle and the alt can't keep up so it pulls power from the battery. Makes sense now.

Black Knight
03-05-2009, 09:36 AM
Ive asked this question along time ago. Its because there are 7 bulbs that light up when you hit the brakes, and those all illiminating at once causes the lights to dim for a second. It does it in all cars. A more powerful battery or LED bulbs could take care of it, thats what Im doing anyway, just to draw less power anyway.

rocketfast123
03-05-2009, 09:44 AM
so there is no real fix than just deal with it?

for the most part, my 2.4 does it when it real cold, but once it waroms up it stops. Our 3100, everything will dim, and only brighten up when you hit the gas.

cardude007617
03-05-2009, 10:10 AM
Ive asked this question along time ago. Its because there are 7 bulbs that light up when you hit the brakes, and those all illiminating at once causes the lights to dim for a second. It does it in all cars. A more powerful battery or LED bulbs could take care of it, thats what Im doing anyway, just to draw less power anyway.

Won't you need resistors possibly to tell the car the bulb is not dead due to less power consumption than normal?

rocketfast123
03-05-2009, 02:47 PM
Won't you need resistors possibly to tell the car the bulb is not dead due to less power consumption than normal?

only on the the lights that flash

GranGT05
03-30-2009, 07:17 PM
I have this same problem on my 05 gagt.I read that maybe a corroded battery post(screw) could cause it but mine are clean and my battery is not that old. I also have had a problem with my parking lights going out at night and my service vehicle soon light comes on when they do go out,some times they come back on and sometimes i have to stop and turn the car off and back on a few times for the lights to come back on, new to check codes in the body control module. none of my park light bulbs are burned out so not sure why the park lights are doing this,I did have to replaced all three of my 3rd brake light bulbs, not sure if or why that would be the cause. I also have longer than normal crank time sometimes when starting, happens maybe 3 times a week.

GranGT05
04-16-2009, 08:26 PM
My 05 GAGT also does it, the battery terminals are clean, the ground by the air box is clean and the power red wire that bolts to the fuse box is clean also. what the heck is that square plastic piece where the ground hooks to just right of the air box??? It seems there is no fix but it does get annoying.I think if i had one under factory warranty I would take it to dealer and tell them to keep it till they fixed it.