Electrical and Electronic Systems Flashcards

During cranking, a voltage drop greater than about how much across the battery positive cable to the starter indicates excessive resistance?

Answer: 0.5 V

Most manufacturers allow roughly 0.5 V maximum drop across the starter feed cable under cranking load.

What is a generally acceptable maximum parasitic (key-off) battery drain on most late-model vehicles after modules go to sleep?

Answer: About 50 mA

Most vehicles should draw roughly 50 mA or less once all modules have entered sleep mode.

To measure current flow in a circuit with a digital multimeter, how must the meter be connected?

Answer: In series with the circuit

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

A DMM set to ohms reads 'OL' when connected across a wire. What does this indicate?

Answer: An open circuit

OL means the resistance is beyond the meter's range, which indicates an open circuit.

Under load, a good ground-side connection should typically show a voltage drop of no more than about:

Answer: 0.1 V

Ground circuits should drop about 0.1 V or less; more indicates resistance.

With the circuit powered, a technician probes both test points on top of a blade fuse with a test light and both sides light. What does this indicate?

Answer: The fuse is good

Voltage present on both sides of the fuse means current can pass through it, so the fuse is intact.

A fully charged lead-acid battery electrolyte at 80°F should have a specific gravity of about:

Answer: 1.265

A fully charged cell typically reads about 1.265 specific gravity.