Exam 25: Detailed Diagnosis and Sensors

The BARO sensor informs the PCM about changes in weather and ____________________.

A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can produce a usable signal.

The hot wire in the mass airflow sensor is held at a constant ____________________ degrees Celsius.

The MAP sensor used on a turbocharged engine is calibrated the same as a MAP sensor for a nonturbocharged engine.

What types of problems could be caused by a faulty engine coolant temperature sensor?

Two technicians are discussing IAT sensors (intake air temperature). Technician A says the IAT sensor is an integral part of the mass airflow sensor (MAF). Technician B says the IAT is a discrete sensor located in the intake air passages or air cleaner assembly. Who is correct?

A throttle position sensor has ______.

What is the primary function of an onboard diagnostic [OBD] system?

A technician connects a DMM with a MIN/MAX/AVG function to the output of an oxygen sensor. The engine is run at 2000 RPM for several minutes. During the test, the voltage toggles rapidly between 150 and 900 millivolts. At the end of the test, the MAX voltage was .967 V, the MIN voltage was .087 V, and the AVG voltage was .683 V. Technician A says the sensor is faulty and should be replaced. Technician B says there could be a vacuum leak that caused the sensor voltage to have a higher than normal average. Who is correct?

Which statement is NOT true?

A technician is setting up a lab scope to measure a sensor. Technician A says that the vertical voltage scale must be adjusted in relation to the expected voltage signal. Technician B says the trigger slope must be set to positive if the trace begins with a rising voltage. Who is correct?

On some vehicles, actuators can be tested with a scan tool by accessing output state control (OSC) or output test mode (OTM). In this mode, the actuator enabled or disabled, or the duty cycle increased or decreased.

Two technicians are discussing OBD-II monitor readiness status. Technician A says that the vehicle must be driven through a drive cycle that includes several minutes of idle, low-speed cruise, medium-speed cruise, and deceleration before all monitors can be performed. Technician B says all monitors can be performed in five minutes of fast idling. Who is correct?

Some PCM inputs come from another control module through the vehicle network.

Trouble codes are being discussed. Technician A says that the first time the system detects a fault, a pending code is set. Technician B says that a pending code will turn on the MIL light. Who is correct?

The ____________________ sensor tells the PCM that detonation is occurring in the cylinders.

What is a closed loop system?

The engine coolant temperature sensor is typically found in the radiator.

A misfiring spark plug can cause a false oxygen sensor reading.

If the MIL light is ON, there will be a DTC and associated freeze frame data stored in the PCM's memory.