# Brake Light and Battery Light



## csagenlee (Oct 18, 2010)

Hello,

I have had this problem before and I know it has to do with the charging system but I have never had this specific set of symptoms so I have no idea where to being with troubleshooting this problem.

I started my 1998 Frontier 4x4 2.4L and the brake and battery light was on, within minutes they shut off but I was monitoring the battery voltage with a bluetooth adapter plugged into my OBD II slot and a 20 minute drive I had anywhere from 15.2 to 15.5 V with the engine running and once I turned the engine off I had 13.4 V with it slowly discharging which it has always done since I put my new battery in this summer.

Once I turned off the truck but had the ignition in the on position to read check engine codes to see if it had thrown any new ones the battery and brake light started to blink and I have never had that happen.

Has anyone else run into this or know of anyone who has run into this issue? I did a google search for it but all I got was results with the lights constantly being on. Like I said I have no idea where to begin with this because the battery is less than 6 months old and the alternator is only 2 years old.

Thank you in advance,

csagenlee


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## smj999smj (Jan 1, 2006)

I've never seen the warning lights flash with the key in the "on" position, engine not running. You may want to inspect the charging system wiring for an area that my be shorting. As far as the charging voltage, above 15.2-15.5 volts is on the borderline of overcharging. Typically, you want to see a range between 13.2-15.0 volts and the "norm" for most Nissans is about 14.7 volts. It would seem that your alternator's internal regulator is bad. Overcharging can cause all sorts of issues with the various computers and electronic modules in a vehicles, from false codes to even damaging the modules. It's possible that the short that is causing the flashing is inside the alternator. As far as the voltage dropping when you turn the vehicle off, that is normal. A good battery's static voltage will be at 12.2 volts. It'll take a few minutes for the voltage that exists while the car is running to settle to static voltage when it is shut off.
FYI, my experience with aftermarket alternators and starters has been that they are often unreliable and many of poor quality. I recommend genuine Nissan reman alternators as they are much better quality, but you do pay a bit more for that.


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