Question

view the electrical diagram above. the engines cooling fan motor operates whenever the ignition is switched on, even when the engine is cold. which of the following would cause this continuous fan motor operation.

• excessive resistance at point a
• an open at point b
• a short to ground at point c
• an open at point d

Explanation:

To determine the cause of continuous fan motor operation (ignition - ON even when engine is cold), we analyze each option:

• Excessive resistance at point A: Point A is related to the ECT (Engine Coolant Temperature) sensor's connection to the PCM. Excessive resistance here would likely affect the PCM's temperature sensing but not directly cause the fan to run continuously when ignition is on (it might affect fan operation based on temperature, not keep it on always with ignition on).
• An open at point B: Point B is a connection from the PCM to the fan relay. An open here would break the signal from the PCM to the relay, so the fan relay might not be activated by the PCM. But the fan is running when ignition is on, so this is not the cause.
• A short to ground at point C: Point C is part of the control circuit for the fan relay. If there is a short to ground at point C, it can mimic the signal that would activate the fan relay (like a signal from the PCM when the engine is hot), but in this case, even when the engine is cold (so PCM should not be activating the fan), the short to ground at C can keep the fan relay activated as long as the ignition is on (since the ignition - ON provides power to the circuit). This would cause the fan to run whenever the ignition is on, even when the engine is cold.
• An open at point D: Point D is in the power circuit to the fan motor. An open here would break the circuit to the fan motor, so the fan motor would not run at all.

Answer:

C. A short to ground at point C