Electrical/Electronic Systems Flashcards

When measuring resistance with an ohmmeter, the circuit must be:

Answer: De-energized (power off)

An ohmmeter supplies its own current, so applied voltage will give false readings or damage the meter.

A magnetic-reluctance (variable reluctance) wheel speed sensor produces what type of signal?

Answer: AC sine-wave voltage

A passive reluctance sensor generates an AC voltage whose frequency and amplitude rise with wheel speed.

Two 6-ohm resistors wired in series produce a total resistance of:

Answer: 12 ohms

Series resistances add directly, so 6 + 6 = 12 ohms.

A customer reports dim headlights and slow cranking. Which test should be performed first?

Answer: Battery state-of-charge and load test

Dim lights and slow cranking point to the battery, so testing its charge and capacity comes first.

What is the purpose of a pull-up resistor in an electronic circuit?

Answer: To set a default high voltage on a signal line

A pull-up resistor ensures a signal line reads a defined high state when not actively driven low.

An open neutral safety switch in an automatic transmission vehicle will most likely cause:

Answer: No crank in Park or Neutral

The neutral safety switch completes the starter circuit only in Park or Neutral; if open, the starter won't engage.

On a CAN bus network, what termination resistance should be measured across the two data wires with the system off?

Answer: About 60 ohms

Two 120-ohm terminating resistors in parallel produce a combined reading of about 60 ohms.