Headlights dim when window switches are used

[Jagster]

I have a '06 5 with 40k miles on it. The headlights dim whenever I use the power windows. Is this normal for this car? My battery was getting pretty weak so I replaced it at about 30k but the dimming issue persists. This happens no matter if I'm idling or cruising down the highway. Last night we were going up I-95 at about 80MPH and the headlights were very noticably dimming when I pushed the power windows switch.

Anyone else have a problem like this?

 

[VenomDesign]

Alternator !

 

[George in GA]

You might check your ground strap. I once had a second-hand '80 Dodge Colt; whenever I turned on the A/C the temp gauge went to hot within 10 seconds. The headlight brightness varied depending on whether or not I was accelerating. It turned out that there was no ground strap, adding one - about $5.00, fixed the problem. NPR's Click and Clack had diagnosed a similar problem on their program and that "inspired" my lucky guess.

 

[antlind]

I have a '06 5 with 40k miles on it. The headlights dim whenever I use the power windows. Is this normal for this car? My battery was getting pretty weak so I replaced it at about 30k but the dimming issue persists. This happens no matter if I'm idling or cruising down the highway. Last night we were going up I-95 at about 80MPH and the headlights were very noticably dimming when I pushed the power windows switch.

Anyone else have a problem like this?

I had the very same problem with my 06. I found it strange and did not pursue the matter with my dealer. We've since sold the car, but what you've described is exactly what I experienced with my 2006 GT. My battery was checked and found to have full charge.

 

[Jagster]

Alternator !

I think it may be the alternator too but I find it odd that there are no problems charging the battery and that even cruising at highway speeds the alternator wouldn't put out enough to push the window motors without causing the headlights to dim.

If it's the alternator, I'm going to be really disappointed. So far I've had numerous problems that should not be happening to a vehicle with less than 30k miles and very well maintained. I've had to have a stalling problem fixed (ECM reprogram), a engine mount burst for no reason (good smooth roads where I live), locks on both sliding doors needed replacing because the motors struggled to lock/unlock, battery failed at 2.5 years, rear tires get worn on the inside and tire shop says they can't get alignment 100% due to wear somewhere (dealer won't look for abmormal wear unless I pay them for another alignment), and this dimming issue. For the most part, I'm happy with the car but I'm worried that there have been a few major issues so early in it's life... I don't feel confident this car can go the distance without some big headaches along the way.

 

[mazdadude]

I think it may be the alternator too but I find it odd that there are no problems charging the battery and that even cruising at highway speeds the alternator wouldn't put out enough to push the window motors without causing the headlights to dim.

If it's the alternator, I'm going to be really disappointed. So far I've had numerous problems that should not be happening to a vehicle with less than 30k miles and very well maintained. I've had to have a stalling problem fixed (ECM reprogram), a engine mount burst for no reason (good smooth roads where I live), locks on both sliding doors needed replacing because the motors struggled to lock/unlock, battery failed at 2.5 years, rear tires get worn on the inside and tire shop says they can't get alignment 100% due to wear somewhere (dealer won't look for abmormal wear unless I pay them for another alignment), and this dimming issue. For the most part, I'm happy with the car but I'm worried that there have been a few major issues so early in it's life... I don't feel confident this car can go the distance without some big headaches along the way.

2006 was a first year vehicle, I have had all of the same issues you have had.

The stalling prob was a TSB, engine mount was a TSB, batteries last 3 yrs, the tires wear excessively due to the camber, and every mazda I have ever owned, dimmed the headlights when rolling windows up or down.(fight) Please, no offense intended, but I think you are being a bit picky for a 4+yr old car.

 

[monsta]

Both of mine will dim if I push the switch when then window is already up. Not too much when they are actually moving. I chalk it up to cost cutting and using the smallest wires possible.

The OEM batteries are junk, too small and probably gets too hot even with the cooling vent

 

[wazza]

Have the same problem on my 2007 1.8 model. Design error? One thing that makes me laugh is that in the manual it states do not operate more than 2 (i think) electric windows as it can overload the system and yet when you use your remote key fob to open the doors and windows it opens all four windows at the same time (with the engine switched off). Where is the overload then?

 

[skyhawk]

Does the head light intensity goes back up when you press on the window button long enough?

The car operates 'efficiently'. Just enough power coming out off the alternator to run the vehicle and the headlights. Sudden additional current loads such as opening of window, or plugging in 12volts accesories, the computer will sense a slight drop in voltage and adjust the field current to the
alternator (this is according to the workshop manual). I figured, there will be a delay.

Just like in my house when washing machine and drier kicks in at the same time.. light dims for a moment but goes back to normal. lol.

 

[zinger002]

find the fuses for the window motors to see how much amperage the manufacturer has allowed them to draw. Most are around the 30 amp range.

Now if you have a stock 100 amp alt, your motor is eating up about, lets say 30-40. then your lights come on and eat up another 20-30 amps. misc other crap may be eating up some. So lets say you have 20 extra amps left over to charge the battery. When you use one window you may use up to 30 amps. so now there is a 10 amp difference that your battery has to make up. start using your rear defroster, ac, heated seats, brights. your maxing out your alternator and your battery is whats then helping run your car.

your stock alt can adjust to put out less, and it does delay untill it notices it needs to work harder, but it cant put out more.

if you got warrenty, i suggest you get them to check its output.

 

[07MZ5SA]

I don't think it's a major issue, mine does it whether power window or air horns.

It's been doing it since day one, even with an Optima battery.

 

[skyhawk]

Today, I tried it on my mz5 2006 GT. idled the car in front of the garage door in the dark with headlights on. I pressed the 4 buttons for window to open.

Result: The headlights remained steady. No dimming. even if all 4 windows are going up and down.

Therefore something is not right in your case.

note: Mine is all stock. No HIDs, no additional stereos, etc.

 

[SGT_OKINAWA]

I have a '06 5 with 40k miles on it. The headlights dim whenever I use the power windows. Is this normal for this car? My battery was getting pretty weak so I replaced it at about 30k but the dimming issue persists. This happens no matter if I'm idling or cruising down the highway. Last night we were going up I-95 at about 80MPH and the headlights were very noticably dimming when I pushed the power windows switch.

Anyone else have a problem like this?

1. WHAT VenomDesign said...

Alternator !

2. Good Gowd people, *sigh* vehicle manufacturers put all this electronic and electrical crap on these cars THEN they get with the motor division and report how many AMPS are needed and guess what.... Motor division puts the bare minimum alternator on the car to save costs. *sigh*

Today, I tried it on my mz5 2006 GT. idled the car in front of the garage door in the dark with headlights on. I pressed the 4 buttons for window to open.

Result: The headlights remained steady. No dimming. even if all 4 windows are going up and down.

Therefore something is not right in your case.

note: Mine is all stock. No HIDs, no additional stereos, etc.

3. ALL CARS ARE DIFFERENT! even with the same make and model cars ARE NOT THE SAME (freak) !

So there is NO COMPARING a Mazda5 2006 in Ohio with a Mazda5 2006 in California. Weather, atmosphere, sea level, mountain level, four seasons, driver habits (lead foot), grade of fuel, type of oil, amount of miles, etc. etc. etc. cars are not the same...

4. Go have a load test out on it at any auto shop, cost about $35 and they can even hook the diagnostic computer up to it and give you a complete read out of everything the PC tests.

5. Eat the discomfort OR buy one of these, I LOVE MY ALTERNATOR NOW, I have (No fibbing ....) 50 ! added electrical things and TWO OPTIMA CCA 800 batteries on my Premacy, I have radar detector, fog lamps, flashing disco lights, 5 AMPS, yup you heard me, 5 POWER AMPS, cross over and power inverter, two PC monitors, a crap load more, like car alarm, illuminated license plates, etc.etc. I think you get the idea well

..... I tested it, ALL THE CRAP ABOVE ON and I OPENED BOTH POWER SLIDE DOORS (Japan & EU Only), HEADLIGHTS ON HIGH BEAM, A/C ON AND FAN ON HIGH, STEREO BLASTING, ALL 4 WINDOWS UP AND DOWS NON STOP and both front and rear wipers on high, AND. Drum ROLL, 4 way flashers and brake lights on guess what. ready for this.. :

My batteries (yes I have TWO) and this sweet alternator did not even hic-up, 160 AMP Alternator only way to roll BABY!! Muahahaah!
Maniac Motors

Good luck, hope you read, some very nice people are trying to help you with this OVER THE INTERNET, and if you did not know, its HARD to diagnose a car OVER THE INTERNET.
Peace!(rei)

 

[mazdadude]

2006 was a first year vehicle, I have had all of the same issues you have had.

The stalling prob was a TSB, engine mount was a TSB, batteries last 3 yrs, the tires wear excessively due to the camber, and every mazda I have ever owned, dimmed the headlights when rolling windows up or down.(fight) Please, no offense intended, but I think you are being a bit picky for a 4+yr old car.

I was re-reading my post, and thought that it might have come across as rude or whatever(argh). If so, it was not intended.(blowup)

My Pioneer Avic stereo head unit has a built in gauge screen where u can look at the battery voltage as one of the options. I have noted on several occassions the battery voltage reading 12.7 volts, however most of the time it reads about 13.4-13.8v with car running. When my headlights dim operating the windows, it is when the windows are already in the fully opened or fully closed postion, and I am trying to continue to operate the window motor in the same direction, binding the motor.

 

[Jagster]

Thanks for all the responses. It sounds like it could be a weak alternator. I've also noticed that the headlights dim when turning the steering wheel any amount. Using the stereo does not seem to affect it. This is a totally stock car.. other than the new tires, battery, and ceramic brake pads. I'm going to take it to the dealer as it's still under the 4yr factory warranty.

 

[mazdadude]

Thanks for all the responses. It sounds like it could be a weak alternator. I've also noticed that the headlights dim when turning the steering wheel any amount. Using the stereo does not seem to affect it. This is a totally stock car.. other than the new tires, battery, and ceramic brake pads. I'm going to take it to the dealer as it's still under the 4yr factory warranty.

Yes, since the steering is electric, this is another load on the electrical system.

 

[mpvue]

at the risk of the sarge saying something sarcastic about my previous car, my Saturn VUE would dim the lights when I rolled the windows up and held the button too long after they were all the way up (not even a second). saturn has a TSB warning not to operate all 4 windows at the same time (as if you could; the buttons were on either side of the shifter, it would take both hands).
anyway, I know it's a different car, but I've experienced dimming lights w/ power windows operating many times. as long as the car doesn't stall, I don't get bothered by it.

 

[bobbyg]

Both of mine will dim if I push the switch when then window is already up. Not too much when they are actually moving. I chalk it up to cost cutting and using the smallest wires possible.

A window motor isn't smart and doesn't know if it is all the way up or not. When you push the button to move it up when it is all the way up, the motor still actives and tries to run. Since it cannot move the motor draws more power as it tries to go. If you held it the button for long enough, the motor would likely over-heat and destroy itself.

So this behavior is completely normal.

And yes, manufacturers will cut costs any way possible and I can guarantee that they're using the smallest possible wires to get the job done. The automotive industry is extremely competitive. Wanna know how much a motor costs new (when it's in mass production, obsolete service parts always cost more to make)? Less than $7.

Keep in mind too that the motor is designed to roll the windows up and down. It isn't designed to run continuously or to run when the window is already all the way closed (or open).

 

[speedracr79]

All it is is when you using you Windows you using voltage to power the Windows its normal there's nothing wrong its happened on every vehicle I've had I just finished my automotive electrical class this semester its just a voltage drop no big deal your car is fine

 

[Robotazky]

If your car is starting right up, like normal, then the alternator is working fine to charge the battery. Sounds normal.