Battery light and brake light coming on and off at the same time

Hello, I had very similar problems with my car. Do you have an automatic starter? My car would keep running if I started with the auto starter, but not if I started normally. Oh well. It could be any number of things, including the alternator. It could also be loose wires on relays. On older cars, these wires can wear or become loose. I would recommend taking to a mechanic for a diagnostic, and hopefully it will be an easy (i.e. inexpensive) fix. Best of luck! CarGrrl

I had this same problem on my Corolla, except mine stayed on. I was driving home from work, and it was dark. the battery and brake lights on the dash came on, and went off a couple of times before staying on. I pulled in to a gas station, and checked the tail/brake lights as I had had trouble in the past with a bad ground in the trunk. Everything was fine. I continued home, and noticed that the dash lights got dimmer and dimmer the further I drove. I was on a rural road, and by the time I made it to another gas station, the dash lights were completely gone, and the head lights were so dim I couldn't hardly see where I was going. The engine even started missing I guess because the electric fuel pump was getting too weak to pump enough gas to the engine. I left the engine running after I pulled into the gas station and turned all of the lights off. I figured that if I turned the car off, I wouldn't get it started again. I happened to have a pipe wrench in my car and used it to turn the bettery terminals thinking that I might have a bad battery connection. The terminals were tight, but the positive connector was pretty corroded. To my surprise, when I looked at the dash the battery and brake lights were off. I turned the head lights on, and everything seemed to be working normally, so I drove home. I restarted the car after I got home to make sure that everything was still working okay. The next morning when I tried to start the car, it was dead as a hammer. That evening, I took the terminals off, cleaned off all of the corrosion on the terminals and the battery posts, coated them with grease to prevent further corrosion, and reconnected them. To my surprise, the car started without needing a jump start. This would seem to confirm the battery terminal problem. I let the car run for a while to make sure that the battery was charged good, and a couple of hours later tried to drive it to the store, and it was dead again, and the brake and battery lights were on again. After a search on the internet, and finding another site where several people had experienced this problem and said that the alternator was the problem, I replaced the alternator. After driving the car for a few miles with no problem, the dreaded battery and brake lights started flickering. I decided to replace the positive post of the battery terminal because it seemed like it wasn't very tight on the battery post. After replacing the terminal, the battery and brake lights were on constant. I had someone sit in the car and monitor the lights while I pulled and twisted on wires under the hood. When I moved the connector on the alternator (the one with multiple connections and a tab that locks it into place), the battery and brake lights flickered as I manipulated it. I cleaned the connector terminals with a wire brush (after disconnecting the battery), reconnected the connector, and haven't had a problem since. Incidentally, the battery and brake lights are the same lights that come on when the key is turned on and the engine isn't running, which would indicate an alternator problem, as the alternator isn't turning at this point. Was the connector the root cause of the problem, or did I also have a bad alternator? I'm leaving it on there anyway because it was the original alternator and the car has 210K miles. Hope this helps.

I had the same issue but mine was just a loose conection with the alt be sure its a Toyota brand if not the life of the alt is 3 months at most

We replaced the alternator on my 2010 Toyota Corolla (85000Km) which was not charging. We also replaced the battery which was 7 years old. The alternator supplier said it was common for the battery to short and take out the diodes in the alternator. My brother replaced the alternator three times on his Nissan maxima before realizing that the faulty battery was causing the alternator failure. You will see a lot of corrosion on the positive terminal too. So change the battery too.

I have a 1990 Geo Prism n the battery/brake light on dash flicker. So I got new battery n one terminal cause other was good. My ex checked the air filter m it was clogged bad We cleaned m.it drove better but lights still flicker