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3rd Gear Chirper
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Indirectly, yes. Example: If the water pump is not flowing enough coolant to keep the engine cool, once it gets hot enough the engine will start pinging, running poorly, etc. The PCM will try to compensate for that until it runs out of "adjustment room". Then the light will come on, probably a spark timing trouble code.

Also, newer Ford modular (and other?) engines have a fail-safe cooling strategy programmed into their PCM's. If the PCM enters the fail-safe cooling mode, the engine light will come on.

The fail-safe cooling works like this: the ECT sensor signals the PCM that coolant temp is rising above normal. The cooling fans will be activated, and the A/C compressor will be disengaged. Timing may be retarded. The drivers temp gauge will indicate the rising temps, and he/she has a chance to pull over and deal with the situation. If this warning goes unheeded the PCM will begin to cut off fuel to half of the engine's cylinders, alternating between cylinders to keep the engine running, although poorly. The reason for this is because the dead cylinders are now acting as air pumps, helping to circulate cool intake air through the engine and slowing the overheating process. If the driver continues to operate the engine under these conditions, the PCM will eventually cut fuel to all of the cylinders, disabling the engine until the coolant returns to an acceptable temperature.
 

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hotbird said:
Also, newer Ford modular (and other?) engines have a fail-safe cooling strategy programmed into their PCM's. If the PCM enters the fail-safe cooling mode, the engine light will come on.

The fail-safe cooling works like this: the ECT sensor signals the PCM that coolant temp is rising above normal. The cooling fans will be activated, and the A/C compressor will be disengaged. Timing may be retarded. The drivers temp gauge will indicate the rising temps, and he/she has a chance to pull over and deal with the situation. If this warning goes unheeded the PCM will begin to cut off fuel to half of the engine's cylinders, alternating between cylinders to keep the engine running, although poorly. The reason for this is because the dead cylinders are now acting as air pumps, helping to circulate cool intake air through the engine and slowing the overheating process. If the driver continues to operate the engine under these conditions, the PCM will eventually cut fuel to all of the cylinders, disabling the engine until the coolant returns to an acceptable temperature.

That's interesting... Out of curiosity, what year did they start that?
 
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