Test Your Diesel Diagnostic Knowledge!

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

Voltage

Amperage

Resistance

Magnetism

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

12 degrees F

15 degrees F

18 degrees F

32 degrees F

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* 3. 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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* 4. 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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* 5. 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 ground circuits are faulty

The Software is not configured

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* 6. 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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* 7. 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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* 8. 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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* 9. 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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* 10. 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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* 11. What is the correct NOx efficiency reduction percentage on “most” commercial diesel vehicles?

100 percent

95 percent

80 percent

60 percent