Jim Grant's Tech Tips
F150, Charging System Problems
Q: Hi, I am having a great deal of trouble
with my ‘96 F150. I have had to install 4 Alternators (brand new), the
last one just yesterday. The Ford dealer has said the alternator is putting
out 14.5 as it should. However when I drive and come to a stop sign/light
my lights are still dimming, and the indicator goes down to N. Is there
something else I should check that the dealer is missing?
would suggest having the battery checked more closely, it could be failing.
A failing battery can have enough electrical energy to crank the engine
for starting. But once the engine is running could create an electrical
load that can easily cause the early demise of an alternator by overworking
it. Have the charging system tested not for voltage output but for amperage
output. A high amperage reading would indicate a problem elsewhere that
is damaging the alternator.