ASE School Bus Diesel Engines (S2) — Information & Free Practice
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ASE School Bus Diesel Engines (S2)
- Provider
- Prometric test centers
- Format
- Computer-based multiple-choice initial certification examination in English; appointment at a test center required.
- Exam questions
- Total questions: 65; Scored questions: 55; Unscored questions: 10; The total includes the scored and unscored questions.
- Time limit
- 90 minutes
Examination outline
General Engine Diagnosis (27%)
- Complaint verification, road test and maintenance history
- Engine identification, EPA certification and service information
- Engine assembly and compartment leak inspection
- Wiring harness, connectors, seals and locks
- Engine noises and vibrations
- Exhaust odor, smoke, volume and opacity
- Fuel supply, return, contamination, quality and consumption
- Air intake restriction and leakage
- Intake manifold and system pressure
- Exhaust back pressure, temperature, soot and ash
- Open and closed crankcase pressure tests
- Cranking, starting and continued running problems
- Engine running, power, acceleration and shutdown problems
- Cooling system condition and operation
- Lubrication diagnosis, oil analysis, oil and filter service
- Diagnostic tools, software, DTCs, data and repair verification
- Diesel exhaust fluid system diagnosis
- Physical damage, missing components and tampering
In-Chassis Engine Inspection and Repair (11%)
- Cylinder head assembly removal and installation
- Threaded holes, studs and bolts
- Cylinder head measurements, warpage, damage and passages
- Injector bores, sleeves and seals
- Valves, springs, guides and related components
- Pushrods, rocker components, wiring and brackets
- Camshaft, bearings, followers, endplay and lift
- Engine gear train, timing and position components
- Valve clearance and injector settings
- Pans, covers, accessories, mounts, gaskets and seals
- Engine block assembly inspection and service
- Liner protrusion and counterbore depth
- Crankshaft vibration damper
- Flywheel, flexplate, ring gear and housing
- Cylinders, liners, rods, wrist pins, pistons and rings
- Crankshaft, journals, passages, nozzles and clearances
Lubrication and Cooling Systems Diagnosis and Repair (13%)
- Oil pressure, temperature and warning instrumentation
- Oil pump and drive service
- Oil regulation, bypass valves and filters
- Oil cooler, thermostat, lines and hoses
- Turbocharger lubrication and cooling
- Pulleys, tensioners and drive belts
- Coolant temperature, level and warning instrumentation
- Coolant thermostats, bypasses, seals and restrictors
- Coolant flushing, refilling, bleeding and recycling
- Coolant conditioner, filter, valves and housing
- Coolant pumps, housings, hoses and drives
- Cooling system pressure tests, caps and tanks
- Cooling airflow, fan and controls
- Radiator coverings, shutters and winter fronts
- Engine block heater and auxiliary coolant heating
Air Induction and Exhaust Systems Diagnosis and Repair (16%)
- Air induction piping, cleaner, restriction and drain
- Turbochargers, controls, wastegates and calibration
- Intake manifold, gaskets, sensors and connectors
- Charge air cooler, piping and connections
- Exhaust manifold, piping, muffler and mounting
- Intake heaters, glow plugs and controls
- Exhaust aftertreatment, DEF, SCR, DPF and regeneration
- Exhaust gas recirculation components and circuits
Fuel System Diagnosis and Repair (27%)
- Fuel tanks, protection, valves, lines and fittings
- Fuel transfer, separation, filtration, heating and cooling
- Fuel leaks, aeration, contamination, priming and bleeding
- Low-pressure fuel regulation
- High-pressure injection lines, tubes and seals
- High-pressure common rail fuel systems and controls
- Hydraulic electronic unit injector systems and controls
- Electronic unit injector systems and controls
- Manual, electronic and air throttle controls
- Engine protection and shutdown or derate systems
- Fuel-system electrical connections and harnesses
- Software, injector calibration, parameters and relearning
- Electronic engine control components and circuits
- Electrical measurement and test equipment
Starting System Diagnosis and Repair (6%)
- Battery identification, state of charge, load and capacity
- Battery charging
- Jump starting and auxiliary power
- Battery, cable and terminal service and voltage drop
- Starters, relays, switches, interlocks and solenoids
- Starter current draw
- Starter circuit voltage drop
Examination sources
- Official ASE School Bus Study Guide
p. 4, Introduction, study-guide adoption and Task List
- Official ASE School Bus Study Guide
p. 9, S2 Test Specifications table, complete headers, A-F rows and total
- Official ASE School Bus Study Guide
p. 9, S2 Task List, A heading and task A1
- ASE School Bus Certification Tests
Study Guides, School Bus Study Guide link
- Official ASE School Bus Study Guide
p. 4, Introduction, question formats
- Official ASE School Bus Study Guide
p. 4, Introduction, complete Task List explanation
- Official ASE School Bus Study Guide
p. 4, How Long are the Tests? table, full S2 row under Certification and Recertification headers
- ASE Certification: Need to Know
p. 3, How Do I Become Certified?, step 3
- ASE School Bus Certification Tests
Test Times and Number of Questions, introductory note
- Official ASE School Bus Study Guide
p. 4, How Long are the Tests? table, asterisk footnote
- ASE Certification: Need to Know
p. 3, How Do I Become Certified?, steps 1-2
- ASE Test Center Policies and Procedures
90 Days to Take Your Test
- ASE Work Experience Requirements
ASE Work Experience Requirements, before experience table
- ASE FAQs
ASE Test Requirements, What is unique about the Advanced Level Tests (L1, L2, L3, and L4)?
- ASE Certification: Need to Know
p. 4, What Are My Certification Options?, Test Centers
Related license preparation
This examination may be required or accepted as an alternative, depending on the license and application pathway.