Ohm's Law & Circuit Math
This law explains the relationship between voltage, current, and resistance.
What is Ohm's Law?
This tool is most commonly used to measure voltage, resistance, and current.
What is a Digital Multimeter (DMM)?
This switch turns on the brake lights when the brake pedal is pressed.
What is the brake light switch?
This connector is used to connect a scan tool to the vehicle.
What is the OBD-II connector?
A technician is diagnosing an electrical problem. What should always be reviewed before testing?
What is the manufacturer's service information or wiring diagram?
In a series circuit, the total resistance is found by doing this.
What is adding all the resistances together?
When diagnosing an electrical component, these two things should always be checked first.
What are power and ground?
This device makes the horn work without sending high current through the horn button.
What is a relay?
This module controls many of the vehicle's body electronics.
What is the Body Control Module (BCM)?
A battery dies overnight. The measured key-off current is 0.20 amps. What should the technician do next?
What is remove one fuse at a time to isolate the circuit causing the drain?
As more resistance is added to a series circuit, this happens to current.
What is current decreases?
This type of circuit fault has a broken path that prevents current flow.
What is an open circuit?
This component helps prevent radio interference from the blower motor.
What is the blower motor capacitor?
Before clearing codes, technicians should always do this.
What is record the DTCs?
A horn has good voltage but does not sound. What component should be checked next?
What are the ground, relay, and horn itself?
Adding more branches to a parallel circuit causes this to happen to total resistance.
What is total resistance decreases?
This condition can cause motors or lights to work poorly even though voltage is present.
What is high resistance?
This brake light must also be tested during diagnosis.
What is the Center High-Mounted Stop Light (CHMSL)?
Normal key-off battery draw should be less than this value.
What is 0.05 amps (50 milliamps)?
A headlight is dim even though battery voltage is present. What is the most likely cause?
What is a poor ground or high-resistance connection?
A 12-volt circuit has three resistors in parallel. A fourth branch is added. What happens to total current?
What is total current increases because total resistance decreases?
A blower motor has battery voltage at the connector but runs very slowly. Ground is good. What is the next likely problem?
What is excessive resistance in the circuit or a failing blower motor?
The driver's window works, but none of the passenger windows operate. Where should a technician begin diagnosis?
What is checking the master switch, power supply, and grounds?
While testing a blower motor for radio noise, AC ripple measures 0.85 volts. What does this indicate?
What is excessive AC ripple, possibly caused by a faulty capacitor, wiring problem, or poor ground?
A technician retrieves BCM codes, repairs a wiring fault, and verifies the repair. What is the final step?
What is clear the DTCs and confirm proper system operation?