310T Cheat Sheet 2026

The 30 highest-yield 310T facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is a core component of practical training for technicians? → Preventive maintenance techniques
2. What document is essential to prove eligibility for certification? → Proof of apprenticeship completion
3. When recovering refrigerant from a 310T-compliant truck A/C system, the technician must: → Use EPA-certified recovery equipment and store refrigerant in approved containers
4. What type of valve modulates air pressure to each wheel independently during ABS activation? → Modulator valve (ABS solenoid valve)
5. When mounting dual tires on a truck rear axle, what is the MOST important matching requirement between the two tires on the same axle end? → Both tires must have matching overall circumference (rolling radius)
6. During a brake application, the left front wheel locks up while the right front remains normal. This symptom MOST likely indicates: → A stuck open ABS modulator valve on the left front
7. On a combination vehicle, which valve automatically closes to protect the tractor air supply if trailer air pressure drops rapidly? → Tractor protection valve
8. A truck cab blower motor runs only on high speed. Which component is most likely faulty? → Blower motor resistor or speed control module
9. Which components are inspected to confirm the air dryer is functioning correctly during PM? → Purge valve operation and desiccant cartridge condition
10. A truck's air dryer purge valve is constantly exhausting air. What is the MOST likely cause? → Excessive compressor oil carry-over clogging the desiccant
11. During evaluation of a coach's door system, pneumatically operated doors open slowly but close at normal speed. The MOST likely cause is: → A restricted or maladjusted opening-direction flow control valve
12. A coach technician is replacing fuel filters on a common rail diesel. After installation, the correct bleeding procedure is to: → Use a hand primer pump to fill the filters before cranking
13. The parking brake dash control valve pops out (applies) immediately after it is pushed in. What is the MOST likely cause? → System reservoir pressure is below hold-in threshold
14. When evaluating exhaust back pressure on a diesel engine, a reading of 3.5 inches Hg at rated RPM indicates: → Normal back pressure within acceptable limits
15. What does it indicate when a brake chamber push rod stroke exceeds the maximum allowable limit? → The brakes are under-adjusted or excessively worn, reducing braking effectiveness
16. A truck's cab heater produces warm air only at idle but blows cool air at highway speeds. What is the most likely cause? → Low coolant level causing air pockets at higher RPM
17. What happens to the spring brakes when the parking brake control valve is pushed IN on a truck? → Spring brakes release
18. In a tandem drive axle arrangement, the purpose of the inter-axle differential (power divider) is to: → Distribute torque equally between the front and rear drive axles
19. A Class 8 truck repeatedly trips the low air pressure warning at 60 psi within minutes of starting the engine. What should be checked FIRST? → Compressor belt tension and condition
20. Which test is used to verify the compressor governor cut-in and cut-out pressures? → Governor pressure test using a calibrated gauge at the wet tank
21. An Allison automatic transmission control module (TCM) stores a code for 'transmission range inhibit.' What does this indicate? → The gear selector position sensor disagrees with the actual range selected
22. A technician hears air leaking from the exhaust port of the brake application valve when brakes are fully released. This indicates: → A leaking primary or secondary inlet valve seat
23. Which of the following symptoms is most commonly associated with a clogged fuel filter in a heavy-duty truck? → Loss of power, especially during acceleration or when climbing grades
24. During a transmission fluid analysis on a heavy-duty automatic, the technician finds the fluid is milky white. What does this indicate? → Water or coolant contamination
25. A hydraulic lift gate on a truck drops slowly under load even though the pump motor runs continuously. What is the MOST likely cause? → A worn or bypassing hydraulic pump
26. What tool is used to accurately measure the push rod stroke of a brake chamber to determine if it exceeds the adjustment limit? → Steel ruler applied at full brake application
27. On a tractor-trailer combination, the trailer supply valve (also called the tractor protection valve control) is normally what color? → Red
28. Camber angle is described as positive when: → The top of the wheel tilts outward away from the vehicle centerline
29. What tool is used to measure brake lining thickness on a drum brake system during PM? → Dial caliper or purpose-built lining gauge
30. Which measurement tool is used to check diesel injection timing by detecting pressure rise in the fuel system? → Diesel timing light with clamp-on transducer