Electrical and Electronic Systems Flashcards

To measure circuit current directly with a digital multimeter, the meter must be connected:

Answer: In series with the circuit

An ammeter must be placed in series so all circuit current passes through it.

Before measuring resistance of a component with an ohmmeter, the technician should:

Answer: Disconnect power from the circuit being tested

Ohmmeters use their own internal battery, and external voltage causes false readings or meter damage.

A voltage drop test across a ground connection reads 1.2 volts while the circuit operates. This indicates:

Answer: Excessive resistance in the ground connection

Ground connections should drop only a few tenths of a volt, so 1.2 V shows unwanted resistance.

A permanent-magnet power window motor changes direction by:

Answer: Reversing the polarity applied to the motor

The switch reverses polarity across the PM motor's brushes to reverse rotation.

A blower motor operates only on the high-speed setting. The most likely cause is:

Answer: An open blower motor resistor

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

A Hall-effect crankshaft position sensor typically produces what type of output signal?

Answer: Digital square-wave signal

Hall-effect sensors switch on and off, producing a digital square wave.

After disconnecting the battery before servicing a steering wheel airbag, the technician should:

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

The SRS module's reserve energy can deploy the airbag until it discharges, so the specified wait time is required.