Block E: Electrical and comfort control Flashcards
Which specific gravity reading taken at 20 degrees C, would indicate that a lead acid battery was fully charged?
a. 1.100.
b. 1.165.
c. 1.225.
d. 1.265
d. 1.265
A 100% charged lead acid battery should produce a specific gravity reading of positive 1.265 at 20 degree C.
After performing a hydrometer test on a fully charged battery, cell 1 has a specific gravity of 1.279 and cell 2 has a specific gravity of 1.225. What should be done with this battery?
a. Recharge and test.
b. Return to service.
c. Replace.
d. Replace electrolyte.
c. Replace.
Because the variation between the specific gravity in the two cell is greater than 0.050 on a fully charged battery, the battery should be replaced.
A heater fan is not working correctly in a vehicle. It was replaced with a new motor but still does not have adequate speed. What tests should the tech perform with a DVOM to determine the circuit problem?
a. Check voltage drops in the circuit, then
check for current draw.
b. Check resistance of the motor, then
check for current draw.
c. Check voltage at the motor, then test
grounds.
d. Check the grounds for the circuit, then
test voltage at the motor.
a. Check voltage drops in the circuit, then check for current draw.
A tech is checking a no-crank condition on a vehicle. After installing an appropriate test meter, the tech notes an extremely large draw and the cables from the battery to the starter seemed to jump. What would cause this condition?
a. The starter has shorted hold-in windings.
b. The starter has an open field winding.
c. The engine is seized or is mechanically
locked.
d. The resistance in the starting circuit is
high.
c. The engine is seized or is mechanically locked.
The fuel pump keeps running after the ignition key is switched off. What could cause this? a. Oil pressure switch is grounded out. b. Fuel pump relay contacts are stuck closed. c. PCM fuel pump control is grounded. d. Fuel pump relay control open.
b. Fuel pump relay contacts are stuck closed.
The hazard warning lights do not flash when the switch is activated. The signal lights work normally. The same bulb is used for both circuits on this lighting system. What causes this problem?
a. A faulty ignition switch
b. A fault in the signal light flasher
c. A fault in the signal light wiring
d A faulty hazard flasher
d. A faulty hazard flasher
While diagnosing an inoperative power window, a tech notes that the passenger side power window will operate in one direction only (down). What component failure would cause this?
a. Circuit breaker
b. Regulator
c. Window switch
d. Window motor.
c. Window switch.
A trailer with electric brakes is being diagnosed for poor brake application when loaded. The tech has set the gain on the controller correctly and confirmed that power is available at the trailer’s wheels. How should the tech proceed to determine the fault?
a. Measure the current flow in the brake circuit to each wheel to verify the connections are secure.
b. Check resistance of the magnets and
compare them to each other.
c. Monitor the brake controller voltage and
replace the magnets at each wheel.
d. Check the polarity of the magnets with a
compass to verify operation of each
wheel.
a. Measure the current flow in the brake circuit to each wheel to verify the connections are secure.
Which statement is true for gauge type or warning lamp systems?
a. When a balancing coil gauge indicates a
high reading, the sending unit will have
low resistance.
b. If all warning gauges in the instrument
cluster read right, the cause is a shorted
ground.
c. When a balancing coil gauge indicates a
high reading, the sending unit will have
high resistance.
d. If all warning gauges in the instrument
cluster read high, the cause is a shorted
feed.
c. When a balancing coil gauge indicates a high reading, the sending unit will have high resistance
Which statement is correct for boost charging a dead battery?
a. The negative cable should be
connected to the charged battery last.
b. The positive cable should be connected
to the charged battery first.
c. The negative cable should be
connected to the dead battery first.
d. The positive cable should be connected
to the charged battery last
b. The positive cable should be connected to the charged battery first.
+ to dead vehicle’s battery positive
+ to running vehicle’s battery positive.
- to running vehicle’s negative and
- to dead vehicle’s engine block
What is the correct sequence for starting system testing?
a. Perform alternator tests, then test
battery voltage.
b. Perform a battery test, then test starter
draw.
c. Remove the starter from the vehicle,
then test the battery.
d. Test the hold-in and pull-in windings,
then test the armature.
b. Perform a battery test, then test starter draw.
When performing heat shrink tubing repairs, what is the correct procedure?
a. Repair a fusible link, then apply the
shrink tubing.
b. Solder the wires, then position the
tubing and apply heat.
c. Cover an insulated butt splice, then tape
the wire.
d. Strip the wire, then apply the shrink
tubing to the copper.
b. Solder the wires, then position the tubing and apply heat.
When replacing an instrument cluster, what precautions must be followed on installation?
a. Replace all fasteners and torque them
specification.
b. Install a static strap, then remove the
cluster from the anti-static bag.
c. Reset the odometer, then record it on
the work order.
d. Remove the lens on the gauge cluster,
then coat it with anti-static spray.
b. Install a static strap, then remove the cluster from the anti-static bag.
A tech checks a CCFOT air conditioning system notices that the low side pressure is 26 psi, and the high side is 210 psi. Discharge air from the vent is 14C. What is the problem in the air conditioning system?
a. Plugged evaporator
b. Temperature blend control door
malfunction
c. Plugged condenser
d. Air distribution control door malfunction.
b. Temperature blend control door malfunction.
The tech installs A/C gauges and operates the air conditioning system. The following readings and symptoms are noted. what is the cause of the problem? High side 210 psi Low side 45 psi Compressor cycle time 10 seconds on and then 4 seconds off a. Faulty compressor b. Plugged condenser c. Plugged evaporator d. Incorrect oil in refrigerant.
c. Plugged evaporator.
What is indicated when the ambient air temperature is 21C, and the pressure of the refrigerant in the storage bottle is 78psi?
a. Normal condition
b. The bottle is overcharged
c. The bottle is undercharged
d. The refrigerant is a contaminated “cocktail”.
d. The refrigerant is a contaminated “cocktail
A customer complains of a lack of heat. The tech notices that engine operating temperature is correct and the lines to and from the heater core are hot. What is causing the problem?
a. Low coolant level
b. Radiator cap pressure too high
c. Air lock in the heater core
d. Temperature blend door malfunction.
d. Temperature blend door malfunction.
A vehicle at 915 m above sea level has a weak radiator cap that can only maintain 1.5 psi of pressure. If the coolant is mixed 50/50, what temperature will the coolant boil?
a. 100C
b. 97C
c. 107C
d. 125C
c. 107C
What is the correct procedure to remove odour from an AC system?
a. Remove the air box, then spray deodorizer onto the evaporator.
b. Remove the air box, then steam clean the evaporator.
c. Remove the air box, then sanitize the evaporator.
d. Remove the heater fan motor, then spray deodorizer on the evaporator.
c. Remove the air box, then sanitize the evaporator.
Which statement is true when repairing or servicing an air conditioning system?
a. A/C systems are evacuated to remove moisture and air from the system.
b. A/C systems are recharged by adding refrigerant according to discharge temperature.
c. Refrigerant recovery of A/C systems is used to reduce customer costs.
d. The labels attached to A/C systems always indicate the correct refrigerant in the system.
a. A/C systems are evacuated to remove moisture and air from the system.
A cooling system is being checked for coolant contamination. The antifreeze is cloudy. What should be done?
a. Test for pH levels, then add a suitable additive package.
b. Drain and flush the system, then add new coolant.
c. Test for electrical conductivity, then add coolant until it meets specifications.
d. Add acid to clean the system, then replace the pH balanced coolant.
b. Drain and flush the system, then add new coolant.
Which of the following test would be most effective in identifying the location of high resistance in a starting circuit?
a. Resistance test with an ohmmeter.
b. Current draw test with an ammeter.
c. Voltage drop test with a voltmeter.
d. Check OBD 11 fault codes.
c. Voltage drop test with a voltmeter.
WHICH OF THE FOLLOWING SHOULD BE TRUE WHEN JUMP-STARTING A CAR WITH A DEAD BATTERY WITH ANOTHER VEHICLE?
a. The last connection should be ground on the dead vehicle.
b. The first connection should be positive on running vehicle.
c. The last connection should be positive on running vehicle.
d. The first connection should be ground on the dead vehicle.
Answer is a. \+ to dead vehicle > \+on running > – on running vehicle > - on dead vehicle.
A starter motor will not crank, and the vehicle headlamps remain bright. Which of the following could account for this condition?
a. Corroded battery-positive terminal.
b. Corroded battery-negative terminal.
c. Field coils in starter shorted to ground.
d. Defective neutral safety switch.
d. : Defective neutral safety switch.
A starter motor will not crank, and the vehicle headlamps dim when the ignition circuit is energized. Which of the following should be checked first?
a. Discharged battery.
b. Corroded terminals.
c. Field coils in starter shorted to ground.
d. Armature shorted to ground
a. Discharged battery.
When checking starter current draw with an inductive ammeter clamp, which of the following should be done?
a. Disconnect the battery ground terminal.
b. Disconnect the alternator.
c. Crank the engine.
d. Run the engine at idle speed
c. Crank the engine.
What is the maximum voltage drop for any given wire connection on an alternator?
a. 0.2 V-DC.
b. 0.5 V-DC.
c. 1.0 V-DC.
d. 1.5 V-DC
a. 0.2 V-DC
What would be the likely result of a poorly grounded voltage regulator?
a. Discharged battery.
b. Burned out alternator.
c. Arcing noise in alternator.
d. Excessively high charging voltage.
d. Excessively high charging voltage
Which of the following is being done to an alternator when battery voltage is applied directly to the field terminals?
a. Shorting.
b. Full-loading.
c. Full-fielding.
d. Zero-loading
c. Full-fielding.
When setting up to test the amperage output of an alternator, where should the clamps of a carbon pile tester be located?
a. Battery positive and battery negative.
b. Alternator B+ and ground.
c. Alternator B+ and Alternator F
terminal.
d. Starter motor positive and alternator
B+
a. Battery positive and battery negative
Where should the leads of a DVOM be placed to check for excessive key-off current drain using an ohmmeter on a vehicle battery?
a. Disconnect battery ground and check between main ground terminal and chassis.
b. Disconnect battery positive cable and check between it and chassis.
c. Suspected current drain cannot be checked with an ohmmeter.
d. Disconnect alternator Battery + and check between it and chassis.
b. Disconnect battery positive cable and check between it and chassis.
The air conditioning system controls humidity by:
a. Drying the air
b. Warming the air
c. Pressurizing the air
d. Melting frost
a. Drying the air.
What is “ambient temperature”?
a. Refrigerant temperature
b. Desired passenger compartment temperature
c. Passenger compartment temperature with system off
d. Air temperature outside the vehicle.
d. Air temperature outside the vehicle
To what percentage of its capacity can a refrigerant container be filled?
a. 100
b. 90
c. 60
d. It depends on the refrigerant type
c. 60.
Heat that is added to a substance which does not result in a temperature change is:
a. Wasted
b. Sensible
c. Specific
d. Latent
d. Latent
High-pressure refrigerant is cooled below its boiling point in the:
a. Evaporator
b. Compressor
c. Condenser
d. Accumulator
c. Condenser.
You are monitoring a compressor clutch coil circuit with a voltmeter and notice a large voltage spike in the control wire every time the coil is de-energized. What should you test next?
a. Nothing, this is normal
b. Compressor diode
c. Compressor coil
d. Compressor switch
b. Compressor diode.
Temperature control is achieved in some systems by moving the:
a. Mode door
b. Recirculation door
c. Bi-level door.
d. Blend door
d. Blend door.
Which of the following is a part of the low side of the air-conditioning system?
a. Receiver-drier
b. Condenser
c. Evaporator
d. Compressor outlet
c. Evaporator.
Pressure on the refrigerant is reduced at the:
a. Expansion valve
b. Accumulator
c. Reed valve
d. Receiver-drier
a. Expansion valve
Pistons in the axial-type compressor are driven by:
a. A driveshaft
b. A crankshaft
c. Elliptical lobes
d. A swashplate
d. A swashplate
The purpose of the compressor clutch diode is to:
a. Turn the clutch on and off
b. Suppress voltage spikes
c. Prevent overheating of the compressor
d. Provide high voltage for activation
b. Suppress voltage spikes
The size of the expansion valve orifice is controlled by:
a. Evaporator temperature
b. Condenser pressure
c. Compressor outlet pressure
d. Refrigerant flow through the accumulator
a. Evaporator temperature
In a fixed-orifice tube system, refrigerant flow is controlled by:
a. Cycling the compressor clutch
b. Adjusting the pintle valve
c. Throttling the suction line.
d. Regulating the accumulator bypass
a. Cycling the compressor clutch
The high-pressure relief valve typically opens at:
a. 150 to 200 psi
b. 250 to 300 psi
c. 350 to 400 psi
d. 450 to 550 psi
d. 450 to 550 psi
The power-steering pressure switch turns the air-conditioning compressor off:
a. When the power-steering belt breaks
b. During high speed maneuvering
c. In stop-and-go traffic
d. During parking maneuvers
d. During parking maneuvers
If a blower does not operate at any speed, first check the:
a. Resistor
b. Relay
c. Switch
d. Fuse
d. fuse
Evacuating removes water from the air-conditioning system by:
a. Boiling it
b. Condensing it
c. Mixing it with the oil
d. Pulling it into the desiccant
a. Boiling it
Which of the following is NOT a recommended method of determining correct refrigerant charge?
a. Refrigerant weight
b. Sight-glass appearance
c. Refrigerant volume.
d. System pressures
c. Refrigerant volume.
Frost on high-side refrigeration fittings may indicate:
a. Too much lubrication oil in the system
b. Restriction in the system
c. Compressor failure
d. Low refrigerant level
b. Restriction in the system
The outlet line from the evaporator should be:
a. Hot
b. Warm
c. Cool
d. Frost-covered
c. cool
If both the low side and the high side show low readings, what might be the problem?
a. Low refrigerant charge or leaks
b. Condenser malfunction
c. Cooling fan malfunction
d. TXV stuck open
a. Low refrigerant charge or leaks
The most common cause of compressor failure is:
a. Belt failure
b. Contaminated refrigerant
c. Insufficient lubrication
d. Clutch failure
c. Insufficient lubrication.
Which of the following is true when refrigerant leaves the compressor in an A/C system?
a. Low-pressure liquid.
b. Low-pressure gas.
c. High-pressure liquid.
d. High-pressure gas.
d. High-pressure gas.
What oil(s) must be used in automotive HFC-134a air-conditioning system?
a. PAG only
b. Mineral oils only.
c. Ester only.
d. PAG and ester in R-12 retrofit systems
d. PAG and Ester in R-12 retrofit sys.
In which of the following components is refrigerant boiled to a vapour?
a. Compressor.
b. Evaporator.
c. Dryer.
d. Condenser
b. Evaporator.
In a 3-position A/C stem valve, what is the normal operating position?
a. Front-seated.
b. Mid-position
c. Back-seated.
d. Open
c. Back-seated.
When evacuating a HFC 134a A/C system, how long should the vacuum reading be held at 29.9 (76 cm) of Hg (mercury)?
a. 30 minutes
b. 15 minutes.
c. 10 minutes.
d. 5 minutes
a. 30 minutes
What type of HFC 134a leak-detection method is most accurate in detecting the smallest leaks?
a. Fluorescent leak tracer.
b. Electronic leak detector.
c. Flame-type propane leak detector.
d. Soapy water solution.
b. Electronic leak detector.
Which of the following is a likely indication of low refrigerant charge in a HFC 134a A/C system?
a. Compressor damage.
b. Higher than normal gauge readings.
c. Noisy compressor operation.
d. Faster than normal clutch switch cycling
d. faster than normal clutch switch cycling
Which of the following HVAC control doors determine whether ventilation air flows through the heater core?
a. Mode door.
b. Defroster door.
c. Blend door.
d. Heater door
c. Blend door.
When replacing a starter that can be shimmed, what is the necessary clearance between the flywheel and the starter pinion?
a. 1/16” (1.59mm)
b. 1/8” (3.18mm)
c. 3/16” (4.76mm)
d. 1/4” (6.35mm)
b. : 1/8” (3.18mm)
When cranking an engine, the starter motor turns over slowly. Which of the following is a probable cause?
a. Neutral safety switch.
b. Worn starter bushings.
c. Low resistance in the negative cable.
d. Excessive battery CCA
b. Worn starter bushings.
A starter motor will not crank, and the headlamps dim when the starting circuit is energized. The battery test is acceptable, and the connections are corrosion-free. Which of the following should be checked next?
a. Positive battery cable for an open circuit.
b. Neutral safety switch for high resistance.
c. Ignition switch for high resistance.
d. Starter mounting for flange corrosion
d. Starter mounting for flange corrosion.