B2U2 Engine Direct Current Electrical System Flashcards
What is the purpose of the starter motor?
Changes electrical energy into mechanical energy to rotate the engine for startup.
What two functions does the starter solenoid accomplish?
First, it moves the mechanical drive to engage the pinion gear into the flywheel. Second, it closes a set of
contacts to energize the starter motor once the pinion gear is meshed with the flywheel.
What occurs when the coil of a crank relay energizes?
The crank relay contacts close providing a path of current flow to the starter solenoid.
Which battery-charging alternator components turn on the alternator when voltage drops below a preset level?
Voltage regulator.
What do you inspect on a starter and a starter solenoid?
Inspect the starter solenoid terminals for corrosion, inspect the starter and starter solenoid for signs of damage and security of mounting bolts, and look for discoloration or other signs of overheating of the starter motor and starter solenoid.
What are the first two things you do when replacing a starter motor and solenoid?
Disconnect the negative cable from the battery terminal and tag and disconnect the electrical leads from the starter motor.
Why must you ensure you keep correct polarity when reinstalling a starter motor?
You may damage the battery and other electrical component.
What can happen if a charging rate is too high?
You can damage the battery.
What must you do before working on a battery-charging alternator?
Disconnect the negative battery cable before working on the battery-charging alternator.
What type of mixture are the spongy lead negative plates and lead peroxide positive plates of a lead-acid cell immersed in?
A diluted solution of 30 percent sulfuric acid and 70 percent distilled water.
What types of batteries are sealed making it impossible to service the electrolyte?
(1) Maintenance free.
(2) Absorbent glass mat.
(3) Gel cell.
How much does the specific gravity of a lead acid battery electrolyte change with temperature?
.004 for every 10 degrees in temperature change.
If the level of a lead acid battery is low, what should you add to the electrolyte to return it to the proper level?
Distilled water
What are the steps in the troubleshooting process?
(1) Perform an operational check.
(2) Analyze the malfunction.
(3) Locate the malfunction.
(4) Perform corrective action.
(5) Perform an operational check.
What are the electrical malfunction symptoms for an open?
(1) Circuit is inoperative.
(2) Protective device does not activate.
(3) Indicator lamps do not illuminate.
What are the electrical malfunction symptoms of a direct short?
(1) An inoperative circuit
(2) The protective device actuated.
What are the electrical malfunction symptoms of a cross short?
(1) Two or more independent circuits operate from one control device.
(2) The protective device may or may not actuate.
What are the electrical malfunction symptoms of a shorted control?
(1) The circuit continues to operate with the control device in the OFF position.
(2) The protective device does not actuate.
What are the electrical malfunction symptoms of a ground?
(1) The circuit is inoperative.
(2) An actuated protective device.
What are the electrical malfunction symptoms of a low power condition?
Sluggish electric motor, lights that are burning dim, or relays that are chattering.
What is the best way to diagnose a shorted cell in a battery?
Use a battery load tester.
Typical electrical system engines use what voltage batteries to provide power to start and operate the engine?
a. 6 or 12.
b. 12 or 24.
c. 18 or 32.
d. 24 or 36.
B. 12 or 24.
Which electrical system component performs two functions––one mechanical and one electrical?
a. Pinion gear.
b. Starter motor.
c. Starter solenoid.
d. Mechanical linkage
C. Starter Solenoid
Which component is the stationary conductor on the battery-charging alternator?
a. Rotor.
b. Stator.
c. Commutater.
d. Rectifier assembly.
B. Stator
How many diodes are used in the rectifier of a battery-charging alternator?
a. 1.
b. 3.
c. 6.
d. 12.
C. 6
What causes the crank relay coil to de-energize causing the starter solenoid to de-energize?
a. Overrun clutch.
b. Speed switch closing.
c. Crank relay speed sensor.
d. Speed switch opening.
D. Speed switch opening
Why do you make sure to reconnect the electrical leads to the appropriate lugs to match the polarity of the battery
a. It does not matter which leads you connect.
b. To make sure that starter solenoid engages.
c. To avoid damage to the battery and other electrical components.
d. To keep the engine from spinning backwards.
c. To avoid damage to the battery and other electrical components.
If you adjust a battery-charging alternator too high, the
a. battery will not charge.
b. battery will be damaged.
c. battery will discharge the extra to ground.
d. voltage regulator will overheat and stop working.
B. Battery will be damaged
If you adjust a battery charging alternator too low, the
a. battery will not reach full charge.
b. battery will store voltage until it reaches full charge.
c. voltage regulator will compensate and provide the correct voltage.
d. battery will be damaged.
A. Battery will not reach full charge
What is the specific gravity of a fully charged lead-acid cell at 80 degrees?
a. 1.256.
b. 1.280.
c. 1.350.
d. 1.560.
B. 1280
In addition to elbow length rubber gloves and a rubber apron, what other safety equipment must you wear when working on batteries?
a. Ear muffs.
b. Ventilator.
c. Face shield.
d. Steel-toed boot
C. Face Shield
The specific gravity of battery electrolyte changes
a. .004 for every 10 degrees in temperature change.
b. .008 for every 25 degrees in temperature change.
c. .027 for every 5 degrees in temperature change.
d. .125 for every 2 degrees in temperature change.
a. .004 for every 10 degrees in temperature change.
Visually check the electrolyte level in each cell of a battery. If the level is low, fill the cell to the proper level using
a. tap water.
b. sulfuric acid.
c. distilled water.
d. potassium acid.
C. Distilled water
What is the first step you take when replacing a battery?
a. Disconnect the positive terminal.
b. Disconnect the negative terminal.
c. Remove the hold down clamp.
d. Remove connecting cables if multiple batteries are used.
B. Disconnect the negative terminal.
When replacing a battery, which step helps prevent corrosion?
a. Ensure battery terminals are seated and tightened.
b. Ensure battery hold down clamp in secured.
c. Ensure positive terminal is put on first.
d. Ensure the negative terminal is put on last.
a. Ensure battery terminals are seated and tightened.
What is the first step in the troubleshooting process?
a. Analyze the malfunction.
b. Locate the malfunction.
c. Perform an operational check.
d. Ensure the equipment is in proper working order.
C. Perform an operational check
Which electrical malfunction do positive and negative conductors making direct contact cause?
a. An open.
b. A cross short.
c. A direct short.
d. A low-power condition.
C. Direct Short
Which electrical malfunction is caused by the contacts of a switch or relay being welded closed?
a. An open.
b. A cross short.
c. A shorted control.
d. A low-power condition.
C. A shorted control
Which electrical malfunction has the same symptoms as a direct short?
a. Ground.
b. Cross short.
c. Shorted control.
d. Low-power condition.
A. Ground
What is the primary reason for engines failing to start?
a. Bad control.
b. Loose wire.
c. Low battery voltage.
d. Bad starter
C. Low battery voltage
One indication that a direct current (DC) charging system is not working correctly is the battery-charging
a. ammeter is reading in a discharged state.
b. ammeter is reading in a charging state.
c. ammeter is reading zero.
d. voltmeter is reading 14 volts, direct current (VDC) in a 12 VDC system.
A. Ammeter is reading in a discharged state
