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Daniel
Daniel, Ford Technician
Category: Ford
Satisfied Customers: 5064
Experience:  Ford Technician
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2003 Ford F350: Diesel Truck..The Battery light comes..intermittently

Customer Question

I've got a 2003 Ford F350 Diesel Truck. The Battery light comes on intermittently. Some times when the engine is on I don't see the light. And, then it will come on. Aside from changing the alternator, what do you suggest?
Thanks
Submitted: 5 years ago.
Category: Ford
Expert:  Daniel replied 5 years ago.

Daniel :

Welcome to Just Answer. We are working on a fast accurate answer Based on the info you have provided. Your time and my time are both Very important.

Daniel :

Hi I am Daniel

Daniel :

I would also clean the starter cables and the other end of the neg battery cable on ground on vehicle

Daniel :

Ford has fusable links from battery to alternator and I would check them also using wiggleing test while using volt meter

Daniel :

Auto zone will also do a free charging test.

Customer:

The starter cables are in good condition and the ground to the vehicle is good. Where are the fusable links from the battery to the alternator?

Daniel :

I will bring you a diagram as they will be from battery to alternaotr

Daniel :

alternator

Daniel :

click here for diagram

Daniel :

above is the hyper link in the click here hyper link

Customer:

The electronics in the alternator, I assume, are solid state. Are there brushes in an alternator?

Customer:

The one line diagram is nice, but physically where are the links?

Daniel :

it has a stator reg

Customer:

Im sorry, but what do you mean by "stator reg"?

Daniel :

You will have to follow wire color and wire id to alternator and when you get to a thicker piece of wire that would be your fusible link

Daniel :

stator regulator

Daniel :

for alternator see description on diagram

Customer:

From your experience, does this sound like a fusible link problem or an alternator issue?

Daniel :

Functionality
With the ignition switch in the ON position, voltage is applied through the warning indicator I circuit 904 (LG/RD) to the voltage regulator. This turns the regulator on, allowing current to flow from battery sense A circuit 35 (OG/LB) to the generator field coil. When the engine is started, the generator begins to generate Alternating Current (AC) which is internally converted to Direct Current (DC) . This current is then supplied to the vehicle's electrical system through the output (B+) terminal of the generator.

Once the generator begins generating current, a voltage signal is taken from the generator stator and fed back to the regulator internally. This voltage feedback signal (typically half the battery voltage) is used to turn off the warning indicator.

With the system functioning normally, the generator output current is determined by the voltage of the A circuit 35 (OG/LB). The A circuit 35 (OG/LB) voltage is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain the correct generator output.

The set voltage will vary with temperature and is typically higher in cold temperatures and lower in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.

Battery Positive Output Circuit 36 (B+) (YE/WH)
The generator output is supplied through the battery positive output (B+) terminal on the back of the generator to the battery and electrical system.

I Circuit 904 (LG/RD)
The I (ignition) circuit is used to turn on the voltage regulator. This circuit is powered up with the ignition switch in the RUN position. This circuit is also used to turn the charging system warning indicator on if there is a fault in the charging system operation.

A Circuit 35 (OG/LB)
The A circuit (battery sense) 35 (OG/LB) circuit is used to sense battery voltage. This voltage is used by the regulator to determine generator output. This circuit is used to supply current to the generator field (rotor). The amount of current supplied to the rotor will determine generator output.

Daniel :

It may be a weak alternator so its good auto zone will put a tester on it for free. they can check battery alternator and starter. if it has a hard time hooking up or being recognized as being hooked up is when you you start thinking about a loose or bad connection.

Daniel :

When a fusible link goes all the way no charging will be cut off completely

Daniel and 4 other Ford Specialists are ready to help you
Customer: replied 5 years ago.
Thanks - I'll have AutoZone check it out.
Expert:  Daniel replied 5 years ago.
Ok good luck let me know how it goes and book mark my profile.