2005 F150 battery question

Asked by Jul 09, 2016 at 11:39 PM about the 2005 Ford F-150 XLT

Question type: Maintenance & Repair

Yesterday while driving home from the office I
noticed that my battery light suddenly lit. Rev
engine it goes out;  no other indication of failure;
that car starts fine runs fine;  all gauges is working

Tonight driving home I noticed that the battery light
was lit the  battery indicator kept dropping dropping
dropping .   Near home all gauges failed; windows
will not close; lights will not turn on;  all indication
internally  of complete electrical failure .

With a diagnostic tool I determined that battery was
low and not charging
I check battery charge confirmed to be low

How can I determine if it's the alternator or just the
battery ?

6 Answers


well at the verry least..if you have a volt metter after you charge the battery and start it ceck the voltage of the + - battery...is it 12.5 or more...rev the engine up some...does the voltage increase? if so good... also these checks are free at most places.. called a VAT test..

1 of 1 people found this helpful.

Check the battery terminals. loose, corroded.

1 of 1 people found this helpful.

Sounds like a dying alternator. HTH. - Jim


For the battery light to come on then go off giving you a warning that the alternator has stopped charging so I agree with Jim.

1 of 1 people found this helpful.

The biggest mistake people make when they see the battery light icon come on is the battery is bad but what it really means is electrical system has stopped charging 95% of time it is the alternator.

1 of 1 people found this helpful.

Here is the BEST and simplest answer I found With The engine operating; Disconnect the negative wire from the battery. If the charging system (alternator) is working properly the engine will not die. If the alternator is bad The engine will stop

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