Technician Diagnostic Knowledge Test

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* 1. Company Survey Number (Diesel Laptops provides this number):

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* 2. Technician Name:

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* 3. Technician Email Address:

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* 4. What best describes the measurement of electrical pressure?

Voltage

Amperage

Resistance

Magnetism

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* 5. The DOC's main function is to?

Create NOX reduction

Create heat for the DPF regeneration process

Create heat for SCR performance

Inject DEF fluid

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* 6. Diesel Exhaust Fluid (DEF) freezes at what temperature?

12 degrees F

15 degrees F

18 degrees F

32 degrees F

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* 7. When performing diagnostics, fault codes that are inactive should always be ignored.

True

False

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* 8. Within a circuit, if the resistance increases (bad connection, faulty terminals…) the current in the circuit will?

Stay the same

Increase

Decrease

Create a voltage spike

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* 9. You are checking a voltage reading at a headlamp, the specification you are given is in Volts. You check the circuit and your multimeter is giving a reading of 653mV. How many Volts is your reading?

6.53V

6,530,000V

.653V

6,530V

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* 10. While working on a vehicle equipped with an EGR system, you find a light coat of soot on the inside of the intake manifold. This indicates an inefficient egr cooler.

True

False

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* 11. You are attempting to connect an electronic service tool to a vehicle and you are unable to read any modules. The service tool connects to similar vehicles without issues. You notice the LED on the datalink adapter does not light up when connecting to the diagnostic port, what is the most likely cause?

The electronic control modules are not receiving power

The cable is bad on the EST datalink adapter

The diagnostic port power and/or ground circuits are faulty

The Software is not configured

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* 12. Which property of electricity creates the movement within solenoids and actuators, such as inside of a starter relay?

Voltage

Amperage

Electromagnetism

Short Circuit

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* 13. A vehicle comes in to the shop with a driver complaint of "Regening too often." You find the dpf full of soot. You should remove and clean the dpf, perform a regen and release the vehicle.

True

False

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* 14. A 2007+ model Diesel vehicle is brought to a technician with a complaint of excessive regeneration, there are no codes within the ECM’s of the vehicle. What is the most likely cause of failure if the DPF outlet temp is 100F degrees higher than the DPF inlet temp during a forced regeneration?

Failed DPF

Shorted DPF outlet temperature sensor

Inefficient DOC

Biased DPF temperature sensor

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* 15. When checking for amperage we need to put our multimeter leads _____ the circuit.

in parallel with (across)

shorted across

in series with (inline with)

All of the above

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* 16. During a regeneration, the doc inlet temp never reaches its target temperature (doesn’t get hot enough), what is the most likely cause?

the DEF doser is failing to energize

poor fuel quality

a plugged aftertreatment fuel injector

a malfunctioning VGT actuator

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* 17. You are checking the J1939 datalink on a heavy duty vehicle, using your multimeter, you check voltage on CAN low to ground, approximately what reading should you have with the ignition on?

2.4V

12V

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* 18. What is the correct NOx efficiency reduction percentage on “most” commercial diesel vehicles?

100 percent

95 percent

80 percent

60 percent

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* 19. How many wires does a typical pressure sensor have if it only measures pressure?

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* 20. A Hall effect sensor is a sensor that can be used to measure speed, position, and proximity. These sensors have three wires. What would the three wires consist of?

Ignition Voltage, Ground, Reference Voltage

Reference Voltage, Ground, Signal Voltage

Signal Voltage, Ignition Voltage, Ground

Ground, Signal Ground, Voltage Reference

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* 21. The best way to keep from damaging a newly installed EGR cooler is to…

Use a vacuum fill station or air lift

Run the vehicle at wide open throttle as soon as it is started

Run the engine until it burps and add more coolant if needed

No special steps are required

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* 22. What is another way 22,000 ohms could be displayed?

2.2 Ohms

2.2k Ohms

22k Ohms

22M ohms

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* 23. If you were working on a vehicle that has an ABS issue, and the vehicle has a two-wire passive inductive speed sensor, what two Multimeter settings would you use to properly diagnose the sensor?

Voltage AC and Resistance

Voltage DC and HZ

Hz and Resistance

Voltage DC and Resistance

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* 24. When diagnosing a J1939 issue, a test light should be used to verify communication on the databus?

True

False

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* 25. Current or Amperage is the flow of electrons through a circuit?

True

False