310T Practical Skills and Training 3

Question 1

A technician is using an inductive clamp ammeter to measure parasitic drain on a truck. Where should the clamp be placed for an accurate reading?

Accepted Answer

Around only the negative battery cable

Answer

Around the positive battery cable only

Answer

Around both battery cables together

Answer

Around any individual circuit fuse leg

Question 2

While diagnosing a no-start condition on a diesel engine, the technician finds cranking RPM is adequate but no injector pulses are detected. The NEXT logical step is to check:

Accepted Answer

Crankshaft and camshaft position sensor signals

Answer

Fuel pressure at the injection pump

Answer

Glow plug resistance values

Answer

Compression across all cylinders

Question 3

A multiplexed body controller on a coach is not responding to inputs. After confirming 12V power and ground are present, what should the technician check next?

Accepted Answer

CAN bus termination resistance (should be 60 ohms at the DLC)

Answer

Fuse for the passenger lighting circuit

Answer

Relay output voltages on the controller

Answer

Sensor supply voltages from the ECM

Question 4

When using a diesel exhaust fluid (DEF) quality sensor scan tool reading, a value below the acceptable specific gravity range indicates:

Accepted Answer

DEF is diluted with water and SCR efficiency will drop

Answer

DEF is over-concentrated and will crystallize

Answer

The sensor is faulty and must be replaced

Answer

The tank is near empty and must be filled

Question 5

A technician performs a cylinder contribution test on a diesel engine. Cylinder 4 shows no RPM drop when cut out. This MOST likely indicates:

Accepted Answer

Cylinder 4 is not contributing to engine output

Answer

Cylinder 4 injector is stuck open

Answer

The fuel system has excessive air entrainment

Answer

The EGR valve is stuck open

Question 6

When replacing a diesel particulate filter (DPF) on a Class 8 truck, the technician must also:

Accepted Answer

Reset the DPF soot and ash load data in the ECM

Answer

Replace the turbocharger compressor wheel

Answer

Replace the EGR cooler simultaneously

Answer

Perform a manual regen before installing the new DPF

Question 7

A coach alternator output test shows voltage is within spec at idle but drops significantly at high electrical load. This MOST likely indicates:

Accepted Answer

High resistance in the alternator output circuit or worn brushes

Answer

A faulty voltage regulator allowing overcharge

Answer

A sulfated battery accepting excessive charge current

Answer

An open diode in the rectifier bridge causing AC ripple