Calling all car people ...

[AndrewGeibel]

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?

[dsirkle]

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.

[fishmommy]

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.

[2kdime]

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.

[Darkice]

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

[DavidG]

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.

[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.

[STORMS]

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

[Patrick Long]

alternator

[West Coast Jungle]

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.