Hello everyone. I have a 99 F150 4x4 with the 5.4 and 99,000 miles. It has recently had an issue with flickering headlights & dash lights from bright to dim. At one point the battery indicator on the dash came on briefly then went out.

This is what I have checked: I have a handheld battery loadtester and the battery checks out fine. I watched the voltage reading from the charging system at idle and it reads just over 14 volts and flickers slightly. Now when I turn on all the lights accessories etc, and apply a load with my tester it drops down to 10 volts.

I figured this to be the alternator and I had my local Napa check it. They said it checked out fine.

So, what am I missing?

Thanks in advance!

 

Sounds like your alternator is going south. Unless it is checked with a load on it, it will probably check OK. Turn on your head lights and AC and then check your voltage with the engine at about 200RPM. Should also be about 14.5 VDC under load. Battery light probably comes on when you are accelerating, and lights go dim, correct?

 

that's right. I'll have it checked again. Thanks