Lesson Plan Originally Created By:
Mike Monahan
**Operation and Testing of Relays (updated) by Mike Monahan
Part of Unit: Fundamentals of Electrical and Electronic Systems
Lesson Plan Overview / Details
In this lesson, the student will be introduced to the Bosch style relay. Terminology, circuit identification and a variety of testing for this device will be covered.
Materials Needed
- A variety of old relays: some functioning, others not.
- 10 foot of 12 gauge wire
- Wire cutters
- Connectors for relay terminals
- Electric tape
- A test board or head lights with additional 10 foot of 12 gauge wire
- Electrical connectors for light connections and battery connectors
Lesson Time
- 2 Class Periods
- 100 Minutes
Standards
California Career and Technical Education Standards
- T.C.C7.1 Understand how to maintain, diagnose, and repair electrical systems.
- T.C.C7.4 Diagnose, service and repair lighting systems.
- T.C.C7.6 Diagnose, service and repair horns, wipers/washers, and other accessories.
- T.C.C7.7 Perform necessary procedures to maintain, diagnose, service and repair vehicle e...
California Academic Content Standards (Reinforced)
- ELA.9-10.R.CAGT.2.6 Demonstrate use of sophisticated learning tools by following technical direction...
2
At the end of this lesson, the student will:
- Understand how to operate and check relays
- Diagnose and repair these relays
- Diagnose, service and repair lighting systems and also repair, diagnose, and service horns, wipers/washers, and other accessories that have relays in their circuits
- Learn the following terminology: Relay, Terminal, Wire Gauge, Fuse/Breaker, Magnet, Coil and Contact set
- Identify the parts of the relay and the circuit
Activities in this Lesson
- Importance of Relays - Hooks / Set
Do this demonstration using actual headlights on high beams.
- Using a test board, show a long wire approximately 15 foot long that runs the head lights.
- Then, show a relay in the circuit . More current to the head lights= brighter lights
- To make this more dramatic, use a longer wire or put on more lights.
- Less voltage drop = more current going where needed.
- headlight diagram [ Download ] This diagram without relay and long wire - showing voltage drop (duller lights)
- headlight-relays.gif [ View Image ] [ Download Original ] A drawing of a head light relay
- Discussion on Function and Testing - Lecture
Discuss the methods for testing relays: the power up method and the ohm meter reading accross the coil.
Show / demonstrate the 9 volt battery trick across the terminals.
- Headlight upgrades Relays.pdf [ Download ] Explanation- with drawings with and without relays
- Relay Circuit 1 - Lab / Shop
Diagram of Bosch style relay - Answer the questions at the bottom of the sheet.
- relay.jpg [ View Image ] [ Download Original ] Inside view of a relay
- Relay Circuit 2 - Lab / Shop
Answer questions at the bottom of page.
- Relays serve several purposes.doc [ Download ] Relay Description
- Relays more than just cars - Closure
Have a quick recap of the testing and function of relays. Share a global perspective for nuclear and power generation - switching stations and the grid.
- video on relays - Demo / Modeling
Terminal identification of a relay - How to check relays in the car and on the bench.
- YouTube- Basic Relay diagram - IOW what goes where.mp4 [ Watch Video ] [ Download Original Video ] Video diagram of the connections of a relay
- YouTube- Auto Repair & Mechanics How to Test a Car Relay.mp4 [ Watch Video ] [ Download Original Video ] Video on bench testing a relay
- YouTube- Relay test.mp4 [ Watch Video ] [ Download Original Video ] Video on car testing of a relay
Assessment
- Assessment Types:
- Demonstrations, Teacher-Made Test,
