Quote:
Originally Posted by Sburn
Ford changed stuff on the engine fans, starting ~2006 or 2007. Even though the fan is driven by the water pump pulley as before, the clutch is controlled by the PCM. And it appears to be more than just on/off control. Looks like the PCM outputs PWM (pulse-width moulation) which controls how much the clutch locks up, which in turn controls the actual speed of the fan. It's a closed loop system because the fan then has a sensor that reports its RPM back to the PCM. There's DTCs for when the PCM commands the fan clutch to engage and but doesn't see an increase in the reported fan speed.
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Sburn - you're an absolute goldmine of knowledge!
(I'm being quite sincere when I say that).
Funny, isn't it, that something as simple as a temperature induced viscosity increaser would have to be replaced by sensors, specialized circuitry in the PCM and probably, a much more complicated clutch mechanism in the fan hub. I suppose that's progress, and I'm sure it's ever so much more precise, but still....
- Jack
Mon, June 15th, 2009, 05:00 PM
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