I have a 2013 f150 lariat with 45,00 miles. Lat week my battery warning light came on after 2 blocks of driving. I took it to O'reileys where they hooked up a battery tester- nothing wrong. I took it to Ford- the light went away, so unless I have a warning light on, their tester would not show anything wrong. The warning comes on 98% of the time, but goes away 100% of the time within 2 miles. New battery? New Altrrnator? Disregard the warning? Buy a new truck?

 

Borrow free code reader from auto parts store and read code when light comes on.

 

did ford run any tests? I am assuming it is out of warranty. Strange they did not find anything that they could end up selling you!

Mine is nearing 3 years, will replace it then.

 

No fees were given, so I assume just a quick chech.. I'm looking at a 2016 lariat now...

 

Do you have anything that you leave plugged into the 12V ports?
Do you have any accessories connected to the battery?

 

Nothing plugged in. On the 2013, if you do not have the key turned on the on position, power is not on.. Nothing in anything.. After driving it yesterday 30 miles, I was going 5 or 10 mph, it came on again, so I think it may be the alternator or a lack of power to abstain all my daughters I pad charging and radar detector...

 

Even at idle the alternator has a substantial load. Fuel pump, injectors, ECU, etc. The power steering is also a large load. I think it is fused for 150A. So if the alternator cannot charge a few accessories, it is definitely faulty. The truck measures it's current and voltage output and so should be able to self diagnose a bad alternator.

 

Thanks.. Took it to Ford today. Alternator seems to be the issue, but warning light not on to check it 4 sure. Ford does not want to change alternator and find out later it is something else...

 

Just use Waze, it's better anyway.

 

Research “Smart Charge” on this forum, disconnect it. (One of the battery cables goes through a coil, take the cable out of the coil.) Something like that.
This is one of Fords bad ideas, the alternator never fully charges the battery.
It saves .0000000000001 mpg.