Exam 4: On-Board Diagnostic Scanners and Digital Storage Oscilloscopes

If everything in the system is functioning smoothly, both LTFT and STFT values should be close to 0.

Repeat component failures may be caused by a defective voltage suppression diode in a relay.

Diagnostic scan tester operation varies depending on the make and model of the scan tool.

What type of signal has a varying voltage within a specified range over a period of time?

Technician A says diagnostic scan tester operation varies depending on the make and model of the scan tool. Technician B says one of the major differences between OBD II and OBD I scan tools is how and where they are connected to the DLC. Who is correct?

What term is used to represent the highest point in one cycle of an AC voltage waveform?

What was the major difference in connecting an OBD II and a pre-OBD II scan tool?

How does the PCM determine catalyst efficiency?

An OBD II scan tool generally offers greater control and more in-depth service information than was available to the service technician with earlier-generation systems and tools.

On an OBD II emission control system, how many oxygen sensors are required?

On a DSO screen, what value is displayed vertically?

While discussing the misfire monitor: Technician A says while detecting a Type B misfire, the monitor checks cylinder misfiring over a 1,000 rpm period. Technician B says while detecting a Type A misfire, the monitor checks cylinder misfiring over a 50 rpm period. Who is correct?

By referring to STFT and LTFT values, the technician can determine how the PCM is reacting to current engine operating conditions.

The CAN protocol will never be a required protocol for all manufactured vehicles.

Beginning in 1996, ODB II vehicles were equipped with a standard 18-pin DLC.

While discussing LTFT and STFT when the STFT number is -20 and the LTFT number is -20: Technician A says these numbers indicate the PCM is trying to decrease fuel delivery. Technician B says these numbers indicate a normal condition. Who is correct?

What is the basic function of all scan tools?

On a DSO screen, what value is displayed horizontally?

What is LTFT and STFT?

On a DSO screen, what will happen if the time base selected is too long and the voltage range is set too high for the circuit being tested?