Instrumentation & Gauges

1. The warning lamp of a charging-system is activated by a:

difference in voltage.
pressure switch.
temperature switch.
variable resistance sending unit.


2. Technician A says the brake warning light is connected into both the parking and service brake systems. Technician B says the brake warning light will come ON only if the service brake system fails. Who is correct?

Technician A only.
Technician B only.
Both Technician A and B.
Neither Technician A nor B.


3. For accuracy, many electrical gauges depend on ________ voltage.

an alternating.
a regulated.
none of the above.


4. If a warning lamp will operate with the ground circuit is bypassed with a jumper wire to ground, what should you check for:

open ground circuit.
defective buzzer .
blown fuse.
open circuit in the 12 volt supply wire to the buzzer.


5. When the sending-unit resistance is low:

a bimetallic gauge reading is high.
a magnetic gauge reading is low
the unit is short-circuited and should be replaced
both a and b.


6. All of the following can cause the temperature lamp to remain off when the ignition switch is turned to the run position, with the engine not running, except:

a blown fuse.
a defective lamp.
a defective sending unit.
an open prove-out (test) circuit.


7. An electronic tachometer:

is gear driven by the transmission.
measures actual vehicle speed.
receives voltage pulses from the injectors.
receives voltage pulses from an ignition signal.


8. Technician A says that a fuel tank sending unit will have a high resistance only when the tank is full. Technician B says that its resistance when the tank is full depends on whether the sending unit is designed for use with a bimetallic gauge or with a magnetic gauge. Who is correct?:

technician A only.
technician B only.
both technician A and B.
neither technician A nor B.


9. To detect that a lamp has burned out, a lamp-out warning system senses: 

current flow to the lamp.
light output of the lamp.
heat produced by the lamp.
a voltage drop across a resistor.


10. The sending unit in the fuel gauge utilizes:

a fixed resistor.
a zener diode.
a float.
a diaphragm.


11. A warning lamp does not light, but it does light when the wire from the lamp going to the sending unit is grounded (the part that plugs into the sending unit) what does this indicate:

the sending unit is defective.
the warning lamp is defective.
there is an open circuit in the lamp wiring.
the fuse is blown.


12. Thermistors are used in which components:

fuel gauge sending units.
oil pressure sending units.
coolant temperature sensors.
temperature switches.


13. All of the following can cause all the gauges to be inoperative in a bimetallic gauge system except the:

sending unit ground connection.
printed circuit wiring.


14. Fiber optic devices conductors:

produce light.
are powered by a 12v battery.
transmit light.
draw a small amount of electric current.


15. Technician A says that an IVR is used to prevent changes in charging system voltage from affecting the gauge readings. Technician B says that an IVR is are needed with a magnetic type gauge:

technician A.
technician B.
both technician A and B.
neither technician A nor B



16. Temperature warning lamps are being discussed. The warning lamp is on while the engine is cranking because the:

sending unit resistance is low.
sending unit contacts are closed.
sending unit contacts are open.
prove-out (test) circuit grounds the lamp.


17. The wire is disconnected from the temperature sending unit (magnetic gauge). A voltmeter connected to the wire reads 0v. What does this indicate?

the sending unit is defective.
the gauge circuit fuse is good.
an open circuit in the gauge circuit.
the gauge circuit is operating properly.


18. The wire is disconnected from the fuel gauge sending unit (bimetallic gauge). A voltmeter connected to the wire reads a pulsating 5v. What does this indicate?

a properly operating IVR (instrument voltage regulator).
the sending unit is operating properly.
A defective IVR (instrument voltage regulator).
a defective fuel gauge.


19. The sending unit for an oil pressure warning lamp circuit is a:

normally open switch.
variable resistor.
normally closed switch.



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