Mitsubishi: Brake and battery light on dashboard ON, alternater, battery problem

Question
Dinger,

    I know you specialize in transmissions, but suspect you have been around enough of the vehicle to give me an idea.

    I started up my car today in NC, and found the brake light and batter light would not go off.

    I had no problem starting it several times, and the temp gages holding well, no noises, etc.

    I replaced the ECM box about a year ago, so I don't think this is it.

    I could probably have driven the 7 miles I needed to go today, but the temp was 90 here, and if the battery is NOT getting properly charged, I could envision the AC unit sucking up the battery REAL QUICKLY.

    I'm thinking alternator, but confused by the brake light also staying on.

    Any insights you can give me would be greatly appreciated.

Thanks,

Frank

Answer
Hi Frank,

You know I just LOVE electrical problems! LOL Ok, what I know about charging systems is this: The way to check to see if it is a battery problem or an alternator is to disconnect the positive side of the battery while it is running. If the car dies then it's the alternater, if not, then it's the battery. I suspect it's alternator here. Brake light being on also, kind of throws a wrench into the whole theory though. Ok, so then not knowing the year and model there is a possiblity of a bad PCM/ECM. Do the battery thing I mentioned, check the fluid in the brake reservor and make sure the e-brake is all the way off and re-submit the info to me. Heck, we'll find it and fix it!