310T COMPREHENSIVE EXAM 2026/2027 QUESTIONS AND
SOLUTIONS RATED A+
✔✔What type of output would you measure from a throttle position sensor described as
"non-contact"?!
WM (pulse width modulation).
DC analogue
AC analogue
3-phase ripple - ✔✔WM (pulse width modulation)
✔✔When you are testing a diode and it conducts equally well both ways, which of the
following is probably true about the state of the diode?!
Forward bias
Reverse bias
Open
Shorted - ✔✔Shorted
✔✔When preparing to boost a set of discharged batteries on a truck chassis, where
should you locate the ground clamp on the truck you are boosting?!
Anywhere on the frame
Alternator ground clamp
Directly to a battery negative post
Directly to a battery positive post - ✔✔Directly to a battery negative post
✔✔A driver complains his radio produces constant static and his newly replaced
batteries are often too discharged to crank the engine. After ensuring that the batteries
are fully charged, which of the following should you check first?!
Alternator AC leakage
Alternator amperage output
Cranking motor ground integrity
Battery warranty - ✔✔Alternator AC leakage
✔✔You are measuring resistance through an NTC (negative temporary coefficient)
thermistor-type temperature sensor and a reading of 75 kilo-ohms is displayed on a
DMM (digital micrometer). What should be done?!
Discard the sensor, resistance should be close to zero
Heat the thermistor using a torch to see if resistance goes up
Cool the thermistor using dry ice to see if resistance goes down
Nothing. Most good thermistors test between 50 and 100 kilo-ohms resistance -
✔✔Nothing. Most good thermistors test between 50 and 100 kilo-ohms resistance
✔✔In order to access any system's ECM (electronic control module) to read system
faults on a truck chassis data bus, which of the following must be accessed first?!
ID (message identifier)
ID (subsystem identifier)
,ID (parameter identifier)
MI (fault mode indicator) - ✔✔ID (message identifier)
✔✔A truck lead-acid battery at 20°C measures 10.5 V across its terminals. After
performing a 2-minute rapid charge, the battery is disconnected from the charger and
when voltage is tested across its terminals, it produces15.2 V-DC. Which of the
following is the more likely explanation?!
Deep cycle battery
Frozen electrolyte
Shorted battery plates
Sulphated battery - ✔✔Sulphated battery
✔✔When troubleshooting a complaint of sluggish cranking on a truck with batteries that
test ok, you observe that one of the battery ground posts is abnormally hot. Which of the
following should be performed first?!
Test for high resistance at the starter motor positive terminal
Voltage drop test across battery cable clamp and post
Remove starter motor and check for high resistance at hold in windings
Voltage drop test across the insulated battery to starter cable - ✔✔Voltage drop test
across the insulated battery to starter cable
✔✔When testing the amperage output of a heavy-duty truck alternator using an amp
clamp, which of the following methods should be used to draw the specified load from
the alternator?!
Turn on all the lights on the rig
Crank the engine for 15 seconds
Use a carbon pile
Create a temporary short at the starter solenoid - ✔✔Use a carbon pile
✔✔When load-testing a fully charged lead-acid battery at 20°C, which of the following
would be the recommended load to be drawn by the carbon pile?!
1/2 of the CCA rating for 15 seconds
100% of the CCA rating for 30 seconds
1/2 of the amp/hour rating for 45 seconds
1/2 of the amp/hour rating for 15 seconds - ✔✔1/2 of the CCA rating for 15 seconds
✔✔When preparing to lead-test a maintenance-free, lead-acid battery, the technician
first checks the integral hydrometer eye and sees that it is clear. What should be done
next?!
Fully charge the battery before attempting to test it
Replace the battery, it has a low electrolyte level
Proceed with the test, the battery is fully charged
Remove the surface charge, then proceed to test the battery - ✔✔Replace the battery,
it has a low electrolyte level
, ✔✔What is the primary function of a gel-cell battery in a truck chassis battery bank?!
Boosts available cranking power
Powers 24V side of 12/24 system
Auxiliary power source when engine is not running
Stabilizes alternator output - ✔✔Auxiliary power source when engine is not running
✔✔If you suspect that a lead-acid battery has frozen, what should you do first?!
Replace the battery
Charge at high amperage
Heat with a propane torch
Trickle charge and observe response - ✔✔Trickle charge and observe response
✔✔which of the following methods should be observed to crank a hard-to-start, truck
diesel engine?!
Crank for 2 minutes, rest for 15 seconds
Crank for 30 seconds, rest for 2 minutes
Crank for 15 seconds, rest for 2 minutes
Crank until the batteries die - ✔✔Crank for 30 seconds, rest for 2 minutes
✔✔When an alternator is full-fielded, which of the following temporarily ceases to
function?!
Rectifier
Rotor magnetic field
Voltage regulator
Stator - ✔✔Voltage regulator
✔✔How are the stator windings in a typical truck alternator configured?!
Wye connection
Delta connection
Twisted triad
Semi-elliptical - ✔✔Delta connection
✔✔What specific charging system component is evaluated when you perform an AC
leakage test?!
Stator
Field windings
Diode bridge
Voltage regulator - ✔✔Diode bridge
✔✔When using a DMM to measure voltage, what would happen if you placed the
negative terminal on the more positive section of a circuit?!
Display reading would be preceded by a MINUS symbol
Circuit dead short through the DMM
DMM fuse failure
SOLUTIONS RATED A+
✔✔What type of output would you measure from a throttle position sensor described as
"non-contact"?!
WM (pulse width modulation).
DC analogue
AC analogue
3-phase ripple - ✔✔WM (pulse width modulation)
✔✔When you are testing a diode and it conducts equally well both ways, which of the
following is probably true about the state of the diode?!
Forward bias
Reverse bias
Open
Shorted - ✔✔Shorted
✔✔When preparing to boost a set of discharged batteries on a truck chassis, where
should you locate the ground clamp on the truck you are boosting?!
Anywhere on the frame
Alternator ground clamp
Directly to a battery negative post
Directly to a battery positive post - ✔✔Directly to a battery negative post
✔✔A driver complains his radio produces constant static and his newly replaced
batteries are often too discharged to crank the engine. After ensuring that the batteries
are fully charged, which of the following should you check first?!
Alternator AC leakage
Alternator amperage output
Cranking motor ground integrity
Battery warranty - ✔✔Alternator AC leakage
✔✔You are measuring resistance through an NTC (negative temporary coefficient)
thermistor-type temperature sensor and a reading of 75 kilo-ohms is displayed on a
DMM (digital micrometer). What should be done?!
Discard the sensor, resistance should be close to zero
Heat the thermistor using a torch to see if resistance goes up
Cool the thermistor using dry ice to see if resistance goes down
Nothing. Most good thermistors test between 50 and 100 kilo-ohms resistance -
✔✔Nothing. Most good thermistors test between 50 and 100 kilo-ohms resistance
✔✔In order to access any system's ECM (electronic control module) to read system
faults on a truck chassis data bus, which of the following must be accessed first?!
ID (message identifier)
ID (subsystem identifier)
,ID (parameter identifier)
MI (fault mode indicator) - ✔✔ID (message identifier)
✔✔A truck lead-acid battery at 20°C measures 10.5 V across its terminals. After
performing a 2-minute rapid charge, the battery is disconnected from the charger and
when voltage is tested across its terminals, it produces15.2 V-DC. Which of the
following is the more likely explanation?!
Deep cycle battery
Frozen electrolyte
Shorted battery plates
Sulphated battery - ✔✔Sulphated battery
✔✔When troubleshooting a complaint of sluggish cranking on a truck with batteries that
test ok, you observe that one of the battery ground posts is abnormally hot. Which of the
following should be performed first?!
Test for high resistance at the starter motor positive terminal
Voltage drop test across battery cable clamp and post
Remove starter motor and check for high resistance at hold in windings
Voltage drop test across the insulated battery to starter cable - ✔✔Voltage drop test
across the insulated battery to starter cable
✔✔When testing the amperage output of a heavy-duty truck alternator using an amp
clamp, which of the following methods should be used to draw the specified load from
the alternator?!
Turn on all the lights on the rig
Crank the engine for 15 seconds
Use a carbon pile
Create a temporary short at the starter solenoid - ✔✔Use a carbon pile
✔✔When load-testing a fully charged lead-acid battery at 20°C, which of the following
would be the recommended load to be drawn by the carbon pile?!
1/2 of the CCA rating for 15 seconds
100% of the CCA rating for 30 seconds
1/2 of the amp/hour rating for 45 seconds
1/2 of the amp/hour rating for 15 seconds - ✔✔1/2 of the CCA rating for 15 seconds
✔✔When preparing to lead-test a maintenance-free, lead-acid battery, the technician
first checks the integral hydrometer eye and sees that it is clear. What should be done
next?!
Fully charge the battery before attempting to test it
Replace the battery, it has a low electrolyte level
Proceed with the test, the battery is fully charged
Remove the surface charge, then proceed to test the battery - ✔✔Replace the battery,
it has a low electrolyte level
, ✔✔What is the primary function of a gel-cell battery in a truck chassis battery bank?!
Boosts available cranking power
Powers 24V side of 12/24 system
Auxiliary power source when engine is not running
Stabilizes alternator output - ✔✔Auxiliary power source when engine is not running
✔✔If you suspect that a lead-acid battery has frozen, what should you do first?!
Replace the battery
Charge at high amperage
Heat with a propane torch
Trickle charge and observe response - ✔✔Trickle charge and observe response
✔✔which of the following methods should be observed to crank a hard-to-start, truck
diesel engine?!
Crank for 2 minutes, rest for 15 seconds
Crank for 30 seconds, rest for 2 minutes
Crank for 15 seconds, rest for 2 minutes
Crank until the batteries die - ✔✔Crank for 30 seconds, rest for 2 minutes
✔✔When an alternator is full-fielded, which of the following temporarily ceases to
function?!
Rectifier
Rotor magnetic field
Voltage regulator
Stator - ✔✔Voltage regulator
✔✔How are the stator windings in a typical truck alternator configured?!
Wye connection
Delta connection
Twisted triad
Semi-elliptical - ✔✔Delta connection
✔✔What specific charging system component is evaluated when you perform an AC
leakage test?!
Stator
Field windings
Diode bridge
Voltage regulator - ✔✔Diode bridge
✔✔When using a DMM to measure voltage, what would happen if you placed the
negative terminal on the more positive section of a circuit?!
Display reading would be preceded by a MINUS symbol
Circuit dead short through the DMM
DMM fuse failure
