Electrical Systems Flashcards

Two 6-ohm resistors are connected in parallel. What is the total resistance?

Answer: 3 ohms

Equal parallel resistors divide: 6 ohms divided by 2 equals 3 ohms.

With the circuit powered, a voltmeter placed across an open switch in a simple series circuit will read:

Answer: Source voltage

With no current flow, there is no drop across the load, so full source voltage appears across the open.

A vehicle undercharges, but the alternator tests good on the bench. What is a likely cause?

Answer: A loose or glazed drive belt

A slipping belt prevents the alternator from spinning fast enough to produce full output.

After disconnecting the battery before servicing an airbag system, what should the technician do?

Answer: Wait the manufacturer-specified time for the reserve capacitor to discharge

SRS modules have a reserve capacitor that can deploy an airbag until it discharges after the specified wait time.

A blower motor operates only on the highest speed setting. What is the most likely cause?

Answer: A failed blower motor resistor

High speed usually bypasses the resistor, so an open resistor kills the lower speeds only.

When jump-starting a vehicle, where should the final negative jumper cable connection be made?

Answer: To an unpainted engine or chassis ground away from the battery

Making the final connection away from the battery reduces the risk of igniting hydrogen gas.

How does an inductive clamp-on ammeter measure current?

Answer: By sensing the magnetic field around the conductor

Current flowing through a wire creates a magnetic field that the inductive clamp senses.