I have a 1988 Ford F150 With 302 EFI and the problem I am having is the battery idiot light
is on. When I got home I checked the battery and replaced the battery Hot wire It was corroded,
and charged the battery. Yet the battery light still remains on. What do I check next? Alternator? Voltage regulator?

Thanks.

 

Make sure both Positive & Negative battery cables are clean & tight . Place a DVOM on the battery and check that you have 12-14V at idle . Do you have an instrument voltage gauge or just the light ? Its possible the alternator is dying , but check its output first.
Paul

 

A favorite subject of mine....chasing electrical circuit ghosts. Since you had corrosion on the battery terminal and your truck is an '88 chances are there is more corrosion (some not even visable). Remove your voltage regulator from the fender and sand the fender and the regulator to bare metal. Re-attach the regulator into a new hole or use a larger size sheet metal screw. This would not be the first time (nor the last) that the corrosion behind the voltage regulator has driven Ford truck owners nuts. Good luck.

 

>Make sure both Positive & Negative
>battery cables are clean & tight . Place a DVOM
>on the battery and check that you have 12-14V at
>idle . Do you have an instrument voltage gauge or just the light? Its possible the alternator is dying, but check its output first.
>

> Paul


Thanks for the reply. I have the voltage gage. It is reading 10volts. The first white mark on the gauge. When I checked the battery, I made sure that both terminals are clean and tight. Since I had to replace the positive battery. I do not have a DVOM so can I use a regular VOM?
Again thanks.

Fred

 

>A favorite subject of mine....chasing electrical
>circuit ghosts. Since
>you had corrosion on the
>battery terminal and your truck
>is an '88 chances are
>there is more corrosion (some
>not even visable). Remove
>your voltage regulator from the
>fender and sand the fender
>and the regulator to bare
>metal. Re-attach the regulator
>into a new hole or
>use a larger size sheet
>metal screw. This would
>not be the first time
>(nor the last) that the
>corrosion behind the voltage regulator
>has driven Ford truck owners
>nuts. Good luck.

Thanks for the reply. I will have to check to see if I have the internal voltage regulator or the external regulator. And even if I do have the internal there was two version of the internal regulator that Ford put out. One is replaceable, the other is not. I might replace the alternator anyway to save time and money.

Fred...

 

Fred ,
Any means to measure the alternator voltage will do be it digital or conventional . Also what Bob suggested wouldnt hurt either . Main thing is to isolate the problem before you spend money needlessly on parts that may still be fine .
Paul