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AMEDEE
AMEDEE, FORD TECHNICIAN
Category: Ford
Satisfied Customers: 25424
Experience:  ASE CERTIFIED TECHNICIAN ADVANCED LEVEL SPECIALIST. Wisconsin certified emissions state inspector
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2010 f150 battery light stays on after new altérnator.

Customer Question

2010 f150 battery light stays on after new altérnator. Battery and alt check out ok.
Submitted: 3 months ago.
Category: Ford
Customer: replied 3 months ago.
I reset controler and deleted code. snap-on says must sit for 8hours with no usage to reset????
Expert:  AMEDEE replied 3 months ago.

Hello and welcome!

My name isCustomerand I can assist you with your question.

Expert:  AMEDEE replied 3 months ago.

I will try my best to answer all of your questions.

However, before we get started, please let me mention a few things.

1. If at any point you would like to speak on the phone, please feel free to request a phone call on your end and I can call you right away.

2. If you dont understand any technical terms or anything that I mention (component tests or theory or operation), please let me know and I will provide you with a more in debt explanation or answer.

3. Please understand that I am here to help you anyway I can.

Your saying the battery and alternator test out good but the charging light remains illuminated on the cluster? Is that correct?

Are there any codes in the computer?

Customer: replied 3 months ago.
batt fault
Expert:  AMEDEE replied 3 months ago.

Can I get your VIN and the code number in the computer?

Customer: replied 3 months ago.
The code was read at the auto store and the truck vin is 1ftfx1ev5afb68215
Expert:  AMEDEE replied 3 months ago.

Thank you for that information.

Was this light illuminated before the alternator was replaced?

Where was the alternator purchased from?

Customer: replied 3 months ago.
light came on and alt was whiningcar quest. it has been load tested 14.2 no load 14.1 full load batt cheched out at 800 cca
Expert:  AMEDEE replied 3 months ago.

Thank you for that information. This battery or charge indicator light is on either because of a bad new alternator or a wiring issue between the PCM and alternator. I would replace the alternator with one from the dealership first and see if that does the trick. If not, then check the wiring to and from the alternator.

Or you can check the wiring to and from the alternator first if you would like. Would you like some info on how to do this?

Customer: replied 3 months ago.
I have checked the wires why are are you assuming alt is bad when it passes all tests?
Expert:  AMEDEE replied 3 months ago.

Because I have seen aftermarket alternators cause the charge indictor light to come on or illuminate on the dash even if they are still charging the battery

Customer: replied 3 months ago.
what would cause this?
Expert:  AMEDEE replied 3 months ago.

A wiring issue going to the alternator or a faulty new alternator

Expert:  AMEDEE replied 3 months ago.

The PCM expects a very specific response on the monitor circuit, it is very important to install an alternator that meets or exceeds factory specifications.

Expert:  AMEDEE replied 3 months ago.

Here is how to check the wiring to the alternator.

The GEN-COM (generator command) signal from the PCM to the alternator. If there is a change in the vehicle's electrical load, such as turning the headlights on or off, a series of rapid battery voltage pulses should normally be seen on this circuit. This is feedback signal from the voltage regulator to the PCM, and is called the GEN-MON (generator monitor) signal. If the GEN-COM signal is OK, but there is no GEN-MON signal from the alternator, disconnect the voltage regulator, and with the key on, check for more than 8 volts on the wire, coming from the PCM. If OK, replace the alternator, making sure to get the correct one for this PCM-controlled system.

Expert:  AMEDEE replied 3 months ago.

Here is a wiring diagram of this circuit.

Expert:  AMEDEE replied 3 months ago.

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