310T Evaluation and Testing Process 3

Question 1

When testing a truck's automatic transmission for slippage, the BEST method is to perform a:

Accepted Answer

Stall speed test comparing RPM against the manufacturer's specification

Answer

A stall speed test measures engine RPM when the torque converter is stalled against the transmission load, revealing clutch pack or torque converter slippage.

Question 2

During functional testing of a truck's ABS system, the amber ABS warning lamp remains illuminated after the vehicle exceeds 6 mph. This indicates:

Accepted Answer

A fault detected by the ABS ECU requiring further diagnosis

Answer

The ABS lamp should extinguish above approximately 4–6 mph once the system self-test passes; continued illumination signals an active fault code.

Question 3

A technician is evaluating cylinder contribution on a diesel engine using a cylinder cut-out test. If cutting out a cylinder causes no RPM drop, this suggests:

Accepted Answer

That cylinder is not contributing power and may have a fuel, injection, or mechanical issue

Answer

A cylinder that is already not firing or contributing negligible power shows no RPM change when cut out, confirming it is a problem cylinder.

Question 4

When performing a voltage drop test on a starter motor circuit on a heavy-duty truck, the maximum acceptable voltage drop across the positive battery cable is:

Accepted Answer

0.5 volts

Answer

Industry standard allows no more than 0.5 volts drop across each heavy cable in the starter circuit to ensure adequate cranking voltage.

Question 5

A coach's air conditioning system is evaluated and the high-side pressure is 375 psi with an ambient temperature of 90°F. This reading indicates:

Accepted Answer

Overcharge of refrigerant or a condenser airflow restriction

Answer

High-side pressures significantly above the normal range for ambient temperature (typically around 200–250 psi at 90°F for R-134a) indicate overcharge or blocked condenser airflow.

(310t) Truck and Coach Technician Certification Practice Test

(310t) Truck and Coach Technician Certification Practice Test

310T Evaluation and Testing Process 3