BATTERY WAS BAD SO I REPLACE IT. ALTERNATOR WENT BAD I GUESS BECAUSE OF THE BAD BATTERY,I HAD IT TESTED SO IT BEING REBUILD. MY QUESTION IS WHY WAS THERE NOT A ERROR CODE DISPLAYED . I HAD A ALTERNATOR WENT ABOUT 4 YEARS AGO & A CODE CAME AS BAD BATT & ALTER. THIS TIME NOTHING, DOES IT HAVE TO BE COMEPLETY BAD BEFORE A CODE TO BE SHOWN? ANY HELP THANKS

 

Alternator unlikely to go as a result of bad battery.
However bad battery = jump starts which can be VERY bad.
e.g. Reverse polarity, electrical spikes etc. Rectifiers and voltage control in the alternator (and other places) don't like this.

Likely scenario.
Bad battery due to end of life = 3 to 4 years approx exacerbated by cold weather OR alternator not charging correctly leading to "flat" battery.
Once below 12.5 the battery is damaged irreparable ALTHOUGH it may appear to be OK...at least till that inconvenient moment when it decides to let go.
This sudden demise is unpredictable and is as a result of the hidden damage.

Different systems set different codes. The battery symbol is used to convey "Electrical supply problem" rather than specifically battery or alternator.

Starter motor and ignition design has changed significantly over the years to a point whereby the system is shut down (electronic control) rather than being unable to physically turn the motor over (slowly). As I have stated previously this is because electronic systems behave in an unprdeictable way (which may not be "Fail Safe" when operating outside the design voltage range.)

Stuart

 

Replace your voltage regulator before replacing your alternator...the brushes wear out fast on the regulator!

-mar-