• 50 questions

ASE H6 Practice Test

Unofficial transit bus electrical practice in the five content areas of ASE's H6 test, every answer with its source.

Which data rate do SAE J1939/11 and J1939/15 specify for the vehicle network?

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Unofficial practice questions, not affiliated with the National Institute for Automotive Service Excellence (ASE). Bank checked October 13, 2026.

Next step More circuits: ASE T6 truck electricalAll eight H tests: transit bus practice

All 50 questions

General electrical diagnosis 16

  • A clamp-on ammeter is needed for the direct current in a bus charging circuit. Which type of clamp reads DC as well as AC? Wikipedia, Current clamp, Types of current clamp. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • A damaged section of CAN wiring is replaced with two straight parallel wires. Why should the pair be twisted? Wikipedia, CAN bus, Layers. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • A diode is wired across a relay coil. What is it there to stop? Wikipedia, Flyback diode, opening section. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • A door open output is traced on a multiplex ladder diagram. When is a normally inactive coil at the end of a rung energized? Wikipedia, Ladder logic, Syntax and examples. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
Show all 50 questions (46 more)

General electrical diagnosis, continued

  • A lighting circuit breaker of the type with a telltale light has tripped, and the short has been repaired. What may still be needed, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 16-8. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • A long feed to the rear lamps loses too much voltage. What is the easiest way to cut voltage drop in the wire? Wikipedia, Voltage drop, opening section. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • A plain terminal is crimped on a wire under the floor where road splash reaches it. What happens to the wire? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-24. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • Circuit numbers must stay readable on a harness under the bus. Which wire marking does TM 9-8000 call the most durable? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-23. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • Current in a battery cable must be read without opening the circuit. Which tool does that? Wikipedia, Current clamp, opening section. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • On a ladder logic diagram, when is a normally open contact closed? Wikipedia, Ladder logic, Syntax and examples. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • On a schematic, how far does a wire keep the same identification, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-23. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • What does a fuse offer over a circuit breaker? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 16-8. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • What does an oscilloscope show that a multimeter reading does not? Wikipedia, Oscilloscope, opening section. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • Which data rate do SAE J1939/11 and J1939/15 specify for the vehicle network? Wikipedia, SAE J1939, Definition. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • Why does a suppression diode across a solenoid coil not conduct while the switch is closed? Wikipedia, Flyback diode, Operation. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)
  • Wires keep breaking where they enter crimped terminals. Which feature of a solderless terminal prevents this? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-24. ASE H6 content area A, General Electrical/Electronic System Diagnosis (16 of 50 questions)

Battery and starting 12

  • A bus is parked for a long period with its batteries run down. What happens to a battery left this way? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 12-5. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • A hydrometer reading is taken on a very cold morning. How does the temperature affect the specific gravity figure? US Army TM 9-8000, Principles of Automotive Vehicles (1985), chapter 12, specific gravity readings. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • A slave (auxiliary power) receptacle is fitted near the batteries. How is it wired, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-18. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • A starter current draw test is set up on a 24-volt series system with 12-volt batteries. Where do the voltmeter leads go, by the Navy manual? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 4, starting motor current draw test. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • A starter spins fast, yet the engine must turn slowly with high torque. How is the large speed reduction usually obtained? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 14-4. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • How does the rate of discharge change the ampere-hours a battery gives? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 12-5. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • How many lead-acid cells in series make up a 24-volt battery system? Wikipedia, Automotive battery, opening section. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • In a solenoid shift starter, what happens before the solenoid closes the main switch contacts? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 14-4. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • On a solenoid shift starter, what are the two larger terminal posts and the smaller terminal connected to? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 14-4. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • Only alternating current is available in the shop. How can a storage battery be charged? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 12-5. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • What does a cold cranking amperes (CCA) rating state? Wikipedia, Automotive battery, Cranking amperages. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)
  • Why should a battery box keep road salt water away from a damaged lead-acid battery, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 12-10. ASE H6 content area B, Battery and Starting System Diagnosis and Repair (12 of 50 questions)

Charging system 7

  • A low-voltage warning lamp on the dash comes on. What closes its circuit, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-2. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)
  • An alternator charges nothing, and the charge warning lamp never lights with the key on. On a system excited through the lamp, what is a possible cause? Wikipedia, Alternator (automotive), Field regulation. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)
  • The field wire is disconnected at the alternator for an output test with a voltampere tester. What does the Navy manual caution? US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 4, alternator test. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)
  • What puts the no-charge indicator lamp out once the alternator is producing, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 17-2. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)
  • Where is the output current produced in an alternator? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 13-22. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)
  • Why can the brushes of an alternator be much smaller than those of a DC generator? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 13-22. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)
  • Why do the slip rings of an alternator give less trouble than the commutator of a DC generator? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 13-22. ASE H6 content area C, Charging System Diagnosis and Repair (7 of 50 questions)

Lighting systems 7

  • A fluorescent passenger lamp has a ballast in its circuit. What is the ballast for? Wikipedia, Electrical ballast, opening section. ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)
  • The dash lamps cannot be dimmed. On a push-pull headlight switch, what controls their intensity? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 16-7. ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)
  • The dimmer switch and the headlamp switch are both built into the turn signal lever. How are they usually serviced, by TM 9-8000? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 16-7. ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)
  • The hazard warning switch is turned on. What must the lamps do, under FMVSS 108? 49 CFR 571.108, S6.1.5.1. ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)
  • How much light must the outside doorway lamps of a transit bus put on the street surface when the door is open, under 49 CFR 38.31? 49 CFR 38.31, (c). ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)
  • On many vehicles with automatic transmissions, which switch is the backup light switch combined with? US Army TM 9-8000, Principles of Automotive Vehicles (1985), paragraph 16-14. ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)
  • What are daytime running lamps for? Wikipedia, Daytime running lamp, opening section. ASE H6 content area D, Lighting Systems Diagnosis and Repair (7 of 50 questions)

How this list was compiled: Our own questions, written to the test specifications and task list for Electrical/Electronic Systems (Test H6) in the ASE Transit Bus Study Guide (https://ase.com/wp-content/uploads/ASE_TransitBus_Study_Guide.pdf, copyright 2026, read 2026-10-13): A general electrical/electronic system diagnosis 16 questions, B battery and starting system diagnosis and repair 12, C charging system diagnosis and repair 7, D lighting systems diagnosis and repair 7, E related vehicle systems diagnosis and repair 8; total 50. The bank holds the same 16, 12, 7, 7 and 8. Each fact was read on 2026-10-13 in the public text named under its question: US Army TM 9-8000, Principles of Automotive Vehicles (1985), chapters 12 to 14, 16 and 17; US Navy NAVEDTRA 14050, Construction Mechanic, Advanced (1992), chapter 4; 49 CFR 38.31 and 49 CFR 571.108 at ecfr.gov; and Wikipedia for meters, data networks, ladder logic, suppression diodes, battery ratings and door sensors, which the manuals are too old to cover. The sample questions printed in the study guide were not used. Licence: Questions, choices and explanations are original work of this site.

How it works

This free ASE H6 practice test asks 50 transit bus electrical and electronic questions of our own, in the shares of the real test. It is unofficial and not affiliated with, endorsed by or sponsored by the National Institute for Automotive Service Excellence (ASE).

Read the full guide

What the H6 test covers

ASE's Transit Bus study guide divides the 50 scored questions into general electrical diagnosis 16, battery and starting 12, charging 7, lighting 7, and related vehicle systems (gauges, horn, wipers, doors) 8. The bank is built to the same five numbers.

Where the answers come from

Batteries, starters, alternators, lamps and wiring come from Army and Navy manuals. Meters, CAN and J1939 data links, ladder logic, suppression diodes and door sensors come from Wikipedia, because the manuals are older than multiplexed buses.

  • General diagnosis and battery and starting are 28 of the 50 questions. Begin there.
  • For multiplex questions, read the ladder rung: which inputs must be on before the output is.

Questions and answers

How many questions are on the ASE H6 test?

ASE's 2026 Transit Bus study guide gives H6 60 questions and 90 minutes. Fifty are scored. The other ten gather statistics for future tests and look no different. Recertification takes 25 questions in 45 minutes.

Is there an official ASE H6 test study guide?

Yes. ASE publishes a free Transit Bus Study Guide with the H6 test specifications, task list and sample questions. This page is a separate, unofficial practice test built on that outline, and it uses none of the sample questions.

Does H6 count toward Master Transit Bus Technician?

Yes. ASE's study guide marks H3 through H8, along with H1 or H2, as required for ASE Certified Master Transit Bus Technician status. H6 is one of the six.

What does H6 ask that a truck electrical test may not?

H6's task list names multiplex controllers and ladder logic, battery equalizers, passenger lighting with ballasts or inverters, and entrance door switches. For truck circuits, see the ASE T6 practice test.

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