Electrical and Electronic Systems Flashcards
7 cards from real NAPA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical and Electronic Systems flashcards as text
With the battery disconnected, resistance measured between CAN-High and CAN-Low at the DLC should be about:
Answer: 60 ohms
Two 120-ohm terminating resistors in parallel give about 60 ohms.
What is the basic function of a diode in an automotive circuit?
Answer: Allow current to flow in only one direction
A diode acts as a one-way electrical check valve.
Why is a relay used in many automotive circuits?
Answer: To let a low-current circuit control a high-current circuit
A relay uses a small control current to switch a high-current load circuit.
Most engine coolant temperature sensors are NTC thermistors. As coolant temperature rises, the sensor's resistance:
Answer: Decreases
Negative temperature coefficient means resistance falls as temperature rises.
What type of output signal does a typical Hall-effect crankshaft position sensor produce?
Answer: Digital square-wave signal
Hall-effect sensors switch on and off, producing a digital square wave.
Why should a high-impedance (10 megohm) digital meter be used when testing computer circuits?
Answer: It draws very little current and won't damage sensitive circuits
High-impedance meters load the circuit minimally, protecting electronics and giving accurate readings.
When disconnecting a vehicle battery, which cable should be removed first and why?
Answer: Negative, to avoid sparks if a tool touches ground
Removing the negative first prevents a short if the wrench contacts the grounded body.