ASE A8 Engine Performance Practice Test

Diagram of automotive PCM engine control system.

41. There is excessive resistance found at point A in the diagram above. All of the following statements are true about this circuit EXCEPT.

  • A. Excessive resistance in this circuit will result in a lean air/fuel ratio.
  • B. Excessive resistance in this circuit will result in delayed torque converter engagement.
  • C. Excessive resistance in this circuit will result in delayed engine cooling fan operation.
  • D. This is the ground connection for a (NTC) negative temperature coefficient sensor.

41.

Answer A is correct. Faulty inputs result in incorrect actuator adjustments. This is true for fuel injector pulse width and negative or positive fuel trim. The engine runs a startup strategy that enriches the air fuel ratio when the engine's coolant is cold. The ECT sensor affects several different systems, like the air conditioning and transmission.

Answer B is wrong. An engine coolant temperature sensor is a (NTC) negative temperature coefficient sensor. These sensors have less resistance as temperature increases. If there is excessive resistance in this circuit, the PCM will think the engine is cooler than it actually is and delay torque converter engagement.

Answer C is wrong. This will also result in delayed engine cooling fan engagement.

Answer D is wrong. Answer D is wrong. This is because this is an EXCEPT type question. Look for the answer that doesn't fit. This is the ground connection for a (NTC) negative temperature coefficient (ECT) engine coolant temperature sensor.