Calling all car people ...

I have a 2005 Subaru WRX. Over the past few weeks my lights have been flickering. Not just one light but all lights at the same time so I'm fairly confident that it's not wiring. Today my radar detector started giving me low voltage warnings. My battery is less than a year old and it's a top of the line one so I do not think that is the issue. Do you guys think it would be the alternator? Or is it some voltage regulator? The car is driving 700 miles on Monday so I'd prefer if it makes it the whole way. I've never had any problems at all with the car. Anybody got anything?

For many moons the voltage regulator has been located inside the alternator. I am not aware of any exceptions to this but there may be.I know that Subaru's have many things designed differently than what I know about. The voltage regulator is likely the cause. If so, you would have to replace the alternator. Alternators are not cheap so you better have it tested or at least check it with a volt meter at the battery to see how many volts are present before the car is running and while the car is running. A loose or worn and slipping alternator belt could also be causing this. That would be a whole lot easier and cheaper to fix.

If you don't have the tools or the factory service manual, then I would suggest going to your local Autozone store. They can test your alternator right in the parking lot. I don't know if they can specifically test the voltage regulator though - you might try calling them or googling for specific tests you could try with a voltmeter to ferret out the problem.

At first I wanted to say it may be the headlight switch. But if your radar is giving you those warnings, then I too would put money on either the alternator OR the battery. Don't leave the battery out just because it's top of the line. I use an Optima Yellow Top in my car, and even those can go bad.

Did this start doing this all of a sudden? Or have you had any problems leading up to this one?

Agreed, you should go to any local auto parts store and have them test both the alternator and battery.

Check your grounds. And check the both ends of both battery cables. Might be lose or corroded.

Alternator is really the big yellow flag on this one. However, if it was bad it would probably not make your lights flicker so much. They would dim and the car would run out of power. If this was in the shop at work my first diagnosis step would be checking the battery though. If you're in warranty go to the dealership, if not advance auto.

I would say its probably not the alternator. My first check would be for a good ground on the battery. I have had several vehicles that either the battery cables or the ground wire has gone bad. If you have a multimeter check for resistance on the negative wire after removing it from the battery. when you do that check you should have a low reading in ohms. You should also check battery cable to body ground seeing how both the aux. and head lights run off of the body ground not the motor ground.

I would get a volt meter and check the battery before turning on the car. You should get around 12.6 or so. If thats all good, turn on the car and test the battery again - it should have gone up to 13 or 14. If it did, your altenator should be good (that increase shows it is charging you battery). Im not positive about Subarus, but somewhere under the hood there is a fuse box. Make sure the fuse for your altenator is not blown. If it is it could very well cause the low voltage warning & flickering lights ;)

alternator

I would say alternator too. The cheap mans test is to start the car put on the headlights(and other electrical) and then disconect batery terminal(Negative, carefully) so the car is running purely on the alternator. If the lights dim down when battery is removed the alternator is not making sufficient power. You want to make sore your belts are tight, healthy and not slipping, that would also cause a drop in performance.

NOTE: It is safer to remove the negative cable on battery that way if it touches metal on the car it wont short.

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Originally Posted by snakedork

I would say its probably not the alternator. My first check would be for a good ground on the battery. I have had several vehicles that either the battery cables or the ground wire has gone bad. If you have a multimeter check for resistance on the negative wire after removing it from the battery. when you do that check you should have a low reading in ohms. You should also check battery cable to body ground seeing how both the aux. and head lights run off of the body ground not the motor ground.

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with your car running disconnect the battery if it dies then one field of your voltage regulator is bad which is usually built in the alternator.

Ohh yeah, check battery ternimal connections too. If you have a bad connection the alternator will not able to keep the battery charged sufficiently.

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Originally Posted by nixer

with your car running disconnect the battery if it dies then one field of your voltage regulator is bad which is usually built in the alternator.

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yes also if it doesnt die you can put a meter to the posative and negative it should be in the 13 volt range if not it isnt charging at full capacity

Hey guys thank you for all the advice. I would have responded sooner but I'm in mexico for spring break. I will see what I can get done with my car when I get back to Oklahoma next week. The car made the drive. A couple answers to some questions: It started kinda slowly over the period of a few weeks. I do have the tools and a volt meter to check it out myself. And it's not just the headlights. It's every light in the car ... dome lights gauges and everything.

take it to autozone. they will diagnose it for free. sounds like an alternator to me.

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Originally Posted by Darkice

Check your grounds. And check the both ends of both battery cables. Might be lose or corroded.

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+1 NEVER underestimate the power of a crummy ground.My buddy had that problem when he wired his subs. The battery is also linked to the car body, so you may want to check that too. At least on my car, that is directly under the battery.

Hope you find out whats wrong eventually. For all I know you already fixed it, haha. Didn't read the 2nd page.

Alternato!!!!! Is my guess also. And YES if under warrenty by all means go to the dealer. Those are a PAIN to replace on those....Although alot easier w/ the rad., condenser, and fans out the way! lol. Good luck. :gj:

my 90 honda civic ex was doing the same thing, and it appeared at first to be the altenator but then we discovered a wire that was connected to the alternator was eroded, fixed that and it was fine after that. so check both of those out. We figured that out because when he had then connecter to the alternator he was getting good reading, then he moved a wire and the numbers started going bonkers. Good luck

yeah check connections I found the mailman one daytrying to push his car between boxes cause the car died I hooked the battery up and whiel it was pulling acharge i was checking the plugs and the one wire on the back of the alt was loose ( they had replaced it the week before ) and the bolt had backed off. so I tighten it up and suggested he might want ot get some lock tight or a lock nut put on the bolt.. He thanks me every tiem he see me now lol.

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I would say alternator too. The cheap mans test is to start the car put on the headlights(and other electrical) and then disconect batery terminal(Negative, carefully) so the car is running purely on the alternator. If the lights dim down when battery is removed the alternator is not making sufficient power.

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Although that use to work on older vehicles before the invention of the on board computers. I would strongly advise AGAINST doing this. What happens when you do that is the altenator sees zero volts coming in and immediatly full fields the altenator which is okay after it stabilizes. However in those few short moments before it stabilizes it can deliver a voltage spike that is capable of frying your computer.
The only correct way to do it is to either have a battery/altenator tester or just use a volt meter and make sure it's around 13.5 volts+.

Ya I'll get it checked out when I get back to the states on Monday. I actually don't think the alternator is too difficult to replace on my car. It's right on top and you see it every time you open the hood.

I took the car into the Subaru dealer and they checked the alternator and said it was fine. Using my radar detector I checked the voltage at the cigarette lighter and it usually stayed between 10.7 and 11.3 volts. However it jumped around between 10.5 and 12.5. This seems pretty low for a system that is supposed to be at 12 volts. Last year I had a battery go bad due to a loose terminal connection so I replaced it with a top of the line battery. I have heard that a battery going bad cause cause damage to an alternator. I also checked all the grounds and terminal connections and they are clean and secure. I'm at a loss as to what the true problem is. All the evidence points towards the alternator brushes or voltage regulator but the dealership said the alternator checked out. Anybody have any ideas?

UPDATE: I was just out driving around and the voltage was between 13.2 and 14.2 which seems more normal to me. However my lights were still flickering. Another note: the lights do not flicker when running off of the battery when the car is off.

voltage regulator???

thats in the alternator case....but they may have not have checked that???

Have you by any chance put a new sound system in your car?Like amps, subs and such?

i do believe thad be the voltage reg

Ya, I knew the voltage regulator was in the alternator case in my car. I assumed that they would check that while checking the alternator since its internal.

The problem with my radar detector indicating low voltage has become increasingly common so I figure it is something that needs to be taken care of. Plus the flickering lights are very annoying.

Sorry about my slow replies. I am checking this from my non-3G phone. I have done some mild upgrades such as a laser jammer in the grill and a hardwired radar detector. However these are very low current devices. I am interested in a new stereo but won't consider it till these issues are sorted out.

Take all of the after market stuff out and see if the still do it. You're problem shooting so start with easy stuff (stuff you installed.)

When i had my cavalier i had the same issue but it was because i had a system and everything it was on it would dim the lights and everything else cause i didn't have a capacitor. my civic had the same problem you stated. except all the lights would blink and go dead and then come back on and then my speedo wouldnt work, changed alternator still nothing changed battery still nothign took apart all of my dash and put it back together and worked liek a charm lol. maybe a loose wire hidden somewhere. i'd say check the wires in the dash somewhere maybe there is a bare wire that crossed with something else, but definately sounds like an electrical problem if your alternator & batt is good.

I was thinking that if he'd added a sound system that maybe it was drawing off enough for the need of a capacitor. I've seen several cars that needed one. I put a system in my son's GMC Jimmy and added a cap to it to keep the electrical from blinking. He had 2 15 inch subs in a custom box with a 1600 watt amp. The amp needed to be bigger cause it keep overheating trying to power the subs. It probably needed to be about 2400 watts. Oh...I put a 1.5 Farad cap on it to compensate for the electrical draw.

Thanks for the ideas guys. I have taken out both things I installed. Well, not taken them out but unplugged them. Both were hardwired to the 12 V supply that goes to the cigarette lighter. Still got the same flickering. It's been one of those things that started slowly and has gotten worse. So it's some sort of progressive issue. I honestly hope it's the alternator/voltage regulator. I'll take it back to the dealership when I can and see what I can get them to do because it should still be under warranty.

i would check your grounds, battery..also is their any way you can full field your alternator i know its random but it may tell you if your alternator is bad but, if the voltage is flickering it most likely is the regulator

also see if you can get a rebuilt unit..cheaper and often comes with a lifetime warranty..that's what i put on my Audi..hasn't died in 50k miles