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Computer Glitch on a 1999 Subaru?

Hey everyone! You were all really helpful in my post here, so I have a new question.

I have a 1999 Subaru Legacy 5-speed wagon, “Millennium Edition”. Last night when I started it both the brake light and battery indicator lights stayed on. The e-brake was definitely disengaged. I also had a brand new battery and alternator belt installed last June (and the belts were adjusted about a month ago because they had started squealing). The lights stayed on while I drove. The owner’s manual says the brake light could mean that the brake system is not functioning properly and the battery indicator means the battery might not be charging. The manual also suggests I check that the alternator belt is attached. I’m a totally n00b, does anyone know where the alternator belt is on that model and if I can visually see if the belt is attached without having to dismantle anything?

I’m wondering if this is a computer problem, and here’s my thinking. My check engine light is pretty much always on (except right after I get an oil change). This happened about two weeks after I bought the car from the dealership, years ago. When I asked them about it, they told me there was a glitch with that sensor in the '99 model and they told me that it shouldn’t be a real problem (I realize this sounds sketchy, but that’s what they said). Over the winter, my ABS light came on for a 15 minute drive and then went out. The manual says it may have reset itself. Now both the brake light and battery lights are coming on at the same time and it just seems more logical that it’s a computer issue than two things failing at the same time.

Any advice or words of wisdom? Does it seem likely it’s just a computer problem or should I be wary of driving it? Thanks tons for your help!

When the brake system warning light and the alternator/battery warning light are both illuminated (and assuming that the emergency brake is off), this is an indication that your alternator is failing. I would suggest that you have the alternator’s output checked a.s.a.p., as this situation is weakening your battery and could cause you to need a new battery as well as a new alternator.

As to the CEL being constantly illuminated, I don’t buy the dealer’s explanation. Get the codes scanned (free-of-charge) at an auto parts store like Auto Zone and post them back here for some helpful advice on the meaning of the codes.

In the meantime, have a qualified independent mechanic test your alternator’s output before it dies and you find yourself stranded. I don’t recommend that you return to that dealership, based on their statement regarding the CEL!

You’ve let a lot of problems accumulate. Now, it’s potentially a safety problem with the brake light coming on. What do you think we can do for you----make you a mechanic? Can’t. Take your car to an independent shop for these repairs.
If you really wanted to know stuff about this car, you would get a Repair Manual and read it over, and over.

Well, the first commenter was extremely helpful. They were able to tell me a specific problem that could be indicated with both of those warning lights coming on. Your comment is totally unnecessary and unhelpful. If this post bothered you for some reason, scroll on. Considering this issue just started last night, and it’s Saturday so my mechanic is not in the shop, I figured it wouldn’t hurt to ask for some advice before going on a road trip today. I’m not sure what you mean by “let a lot of problem accumulate”. When I had a problem with the alternator in June, I had it checked out and fixed. When I had a problem with my clutch I took it in and had the clutch replaced. Perhaps your reading comprehension is masked by your snarktitude.

Thanks for the response. Not exactly what I wanted to hear, considering I just had the alternator belt and battery replaced in June, but it’s good to know that this might pinpoint a specific issue. Looks like I’ll be seeing my mechanic on Monday!

The advice that VDCdriver (a fellow Soob driver) gave you is correct. The alternator is the problem and is causing those warning lights to turn on. The reason it does this is because the warning lights are in the field circuit for the alternator and it is having trouble, possibly bad brushes inside the alternator. This circuit design also allows the warning lights to be tested when the key is turned from OFF to RUN. The alternator and belt for it are in front of the engine, about in the middle and near the top, very easy to work on. The alternator will have a faily large diameter wire running to it along with a couple of others. The large wire is the alternator output wire and is connected to the battery. The wire carries the high charging current to the battery. It should always have voltage on it so if you work on it, disconnect the negative battery lead first. This problem is pretty common for a Soob this age so this is due to normal ware most likely. A rebuilt unit will get you going again. I recommend you get a remanufactured unit with a lifetime warranty on it.

The computer (ECU or engine control unit) isn’t the problem here. You do need to get this fixed ASAP since the battery isn’t getting charged like it should be.

The technical responses you got aren’t going to help YOUR understanding any. The issue for you to address is, “Is it safe to drive?” The answer is, “No.” You can address any other things, you wish, as you wish.
If you think you can apply any of the knowledge given to you, apply away. You like directness. Fine. You have NO mechanical ability, at all; and little grace.
If you want to stay safe, you can let your mechanic do the repairs. To understand what he does, there are still the repair manuals and Online knowledge sources—such as They are free for the perusal.