Join Date: Aug 2010
Location: Sassamansville, Pa
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I have dual alternators also, but couldn't tell you why some came with single or dual, never really wanted to know!LOL!!!
Here is a copy/paste from another site I'm on.
The charging system is a negative ground system consisting of the following:
- internal voltage regulator
- charging system warning indicator
- storage battery
- necessary wiring and cables
The generator is belt-driven by the engine accessory drive system.
The single generator system consists of the generator mounted on the top right of the engine (diesel) or top center of the engine (gas). The gas
engines use a 3G 115-amp generator with a 2.71:1 pulley ratio. The 6.0L diesel engine uses a 6G 110-amp generator with a 2.79:1 pulley ratio.
The dual generator package consists of an upper/lower dual generator system. The 6.0L upper generator is a VR42 140-amp generator with a 2.79:1
pulley ratio. The 6.0L lower generator is a 4G 120-amp generator with a 3.00:1 pulley ratio. The upper and lower generators are not interchangeable.
In the single generator system, with the key in the ON position, voltage is supplied through the instrument cluster warning indicator I circuit to the
voltage regulator. The regulator grounds this circuit and the charging system warning indicator is illuminated. When the engine is started, the
regulator removes the ground on this circuit and the warning indicator turns off.
On the dual generator system, the PCM controls the charging system warning indicator and commands the lamp on if the PCM detects a concern on
the monitored circuits.
The dual generator system is also monitored and controlled by the PCM. The PCM monitors both the upper and lower generator I circuits to
determine the output of both generators and sets possible diagnostic trouble codes (DTCs). The PCM controls the lower generator by turning it off
when the glow plug system is commanded on by the PCM to avoid possible damage (excessive voltage) to the glow plugs. As soon as the glow plug
system stops cycling, the PCM powers up the lower generator.
The dual generators operate independently of each other. The control is through the internal voltage regulators. If one generator fails, the other
generator can maintain system performance under light load conditions. Under a heavy load, the PCM detects a concern, sets a DTC, and illuminates
the warning indicator.
The set voltage varies with temperature and is typically higher in cold temperatures than in warm temperatures. This allows for better battery
recharge in the winter and reduces the chance of overcharging in the summer.
2004 F350 CC DRW King Ranch
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