Check continuity and resistance in electrical/electronic circuits using appropriate test equipment

Lesson Plan for

DIT 190-191

ELECTRICAL/ELECTRONIC SYSTEMS

Course HS Title: / Electrical/Electronic Systems / Program:
KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
DIT 190 / Electrical/Electronic Systems
Introduction/Context / This lesson will instruct the student on how to check continuity and resistance in electrical/electronic circuits using appropriate test equipment. Knowledge of these techniques and the skills required to correct problems associated with this task are necessary for a student to acquire if they wish to compete for high paying, high skilled jobs in a Diesel Repair Facility. Entry level technicians need to be able to perform this task to 100% accuracy. Incorrectly performing this task can lead to an automobile accident or create customer satisfaction issues.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
Task
Check continuity in electrical/electronic circuits using appropriate test equipment. Check resistance in electrical/electronic circuits and components using appropriate test equipment.
Objective
Given the proper tools and instruction, the student will be able to check continuity and resistance in electrical/electronic circuits using appropriate test equipment, and pass a written test covering the task with 100% accuracy.

Connections:

Skills Standards:
OH 001
OH 002
OH 003
OD 002
OD 003
OD 005
New Common Core Standards:
RST 11-12 3
A-CED-4
N-Q.1
Common Core Technical Standards:
TD-OPS 2
TD-SYS 2
New Generation Science Standards:
HS-PS2-5.
HS-PS3-3.

INSTRUCTIONAL MATERIALS/TECHNOLOGY

Teacher Designed Materials and Other Handouts


Textbooks and Workbooks

Author / Title/ISBN No. / Edition / Publisher / Pages
Various / Electrical/Electronic Systems ASE Test Prep / Fifth / Delmar / 13-14


Equipment

Quantity / Item / Source
As Needed / DVOM / Various


Content/Presentation/Demonstration Outline

Tell students that checking continuity in an electrical circuit is one of the most common troubleshooting rests a technician performs. Let them know that auto-ranging DMMs (Digital Multimeters) do not have to be adjusted to the range that is being measured. Explain that while the purpose of this test is to make sure that a complete current path exists in the circuit being tested, it is important to remember that it is not an accurate indication of circuit performance (e.g., excessive resistance). Tell them a continuity test is most useful to quickly differentiate one circuit from another, such as trying to locate a specific contact in a multiple pin connector.
Instruct students that continuity tests can be made in a number of different ways. If the circuit is energized, a 12/24 volt test light or voltmeter can be used to check for voltage at various test points. Both tools accomplish this by energizing the circuit with low potential current to determine that the circuit can be closed. Explain that many DMMs have a separate feature on them that will allow continuity tests to be made simply by listening for an audible beep. Let them know that this is handy because multiple tests can be made rather quickly, without having to look constantly at the display for a resistance value.
NOTE: Tell students that when testing circuits that include electronic control modules (ECMs), it is essential to observe the original equipment manufacturers (OEM’s) diagnostic procedure to avoid possible damage to the processor.
Instruct students that resistance checks are typically made when a circuit has unwanted voltage drops or low current flow. Inform them that an ohmmeter is a device that circulates a small current through a circuit when it is not energized and then measures the voltage drop through it. It displays this resistance (or restriction to current flow) in units known as ohms. Tell them that the lower the resistance value, the less restriction to electron flow there will be in a circuit.
Explain that if the meter reads infinity (or a high flashing number on most DMMs), this means that the circuit is open. Except for where resistance is built in to a circuit, such as a blower motor resistor or a load itself, generally speaking the lower resistance a circuit has the better. For example, let them know that when testing a length of wire or a fuse, most will test very near zero ohms. Tell students that when testing with a DMM, they should always be sure to zero the meter first to compensate for any resistance present in the test leads, especially when testing low-resistance components or circuits.
Inform students that when making tests with a DMM that is not auto-ranging, be sure to select a range that will provide accuracy. If they are using an analog meter, tell them to set the meter to a range setting that will put the needle in roughly the middle of the scale for the component they are testing.
Tell students that resistance checking of specific components is generally used when a manufacturer specifies a certain test value, such as a fuel level sending unit. Let them know that some components, such as light bulbs and glow plugs, do not lend themselves to resistance testing because their resistance changes as they heat up. Also, large-diameter conductors such as battery cables cannot be reliably tested with an ohmmeter because it cannot circulate enough current to simulate actual operating conditions and identify resistance.


Applications/Practice

1 / Refer to content


Evaluation and feedback Prior to Testing or Lab Work

1 / Objective 1. / Formative assessment / Instructor will observe students as they practice the procedure to assure correct procedure and safety practices are being followed. A checklist will be utilized to chart student progress on the task. Questioning techniques will be utilized as necessary to demonstrate student comprehension / Adaptations and/or accommodations for special needs students will be added if required.


STUDENT ASSESSMENT:(Assess student progress with performance criteria.)

1 / Objective 1 / Summative assessment / written test questions on stated objective / adaptation and / or accommodations for special needs students will be added if required
IMPACT--Reflection/Analysis of Teaching and Learning: (How did students’ progress in relation to the state objectives? Was the instruction successful? Analyze samples of student work particularly that which is unsatisfactory, for the purpose of planning further instruction.)
REFINEMENT--Lesson Extension and Follow-up: (To be filled in as the lesson is modified during initial planning and/or during the teaching learning process.)