Lesson Plan Industry Sector
Transportation

## **Wiring diagram (updated) By Michael Drouin

### Lesson Plan Overview / Details

In this lesson, students will understand, read, and utilize wiring diagrams.

Classroom/Lab
1 Day

### Objectives and Goals

• Students will understand the relationship between the printed wire diagram and the actual wire harness in the automobile.
• Students will outline the electrical systems on the wire diagram.
• Students will locate the grounds on diagram.

### Activities in this Lesson

• Introduction - Lecture

I start by handing out the wire diagram. Then I ask if anyone can Identify the type and model car from the diagram.  I give them a few hints, then I tell them that this car is the single highest production vehicle ever. They made more of these than any other single type of car. Everyone in here has to know at least one person that owns one of these. If your parents were a Hippie they had one, etc.  What is it?  It's a VW Bug! Some one will get it.  I give out a reward, like candy, to a student who figures it out.

• Wire color - Demo / Modeling

I say this represents all the wires used of a VW. In real life, they are not layed out nice and neat like this, but this drawing makes it easy to see and follow the wires. Then I hold up a real wire harness. This is what it looks like installed in the car. The wire diagram is going to help me if I need to sort out problems with the automobiles wiring. I separate a single wire, Show the students the color and direct then to the wire diagram. Notice that the wires are labeled by color on the diagram. Then I ask a couple students, what colors do you see? I usually ask if anyone is color blind at this point.

• Grounds - Assessment

I next review the concept of ground. Every circuit must be complete and the negative must return to the battery. We make the entire car the negative by connecting the ground to the chassis. I then ask them to find, circle and count the grounds on the wire diagram. I point out a couple examples. The light bulb grounds, the spark plug ground etc. Some student will have the total number 29 (I reward him).

• Starting system - Assessment

Next, let's look at the starting system. I ask, what does the starting system do? It turns over the electric motor to spin the engine (give a reward to a correct answer). So we need a power source: the battery. We need an electric motor: the starter. We need a switch: the ignition switch. Then I review why we need a solenoid and what it does. I remind then that if they follow the positive wire from the battery, it will lead them to the starter. Then I have them pick a red crayon out of a big box or a crayon that I have and color all the parts of the starting system red.....components, wires, connections, etc.

• Charging system - Assessment

Next I talk about the charging system. It provides the power to operate the ecletrical devices on the automobile. In the case of the VW it is a generator, regulator. Notice that a wire connects to the battery so it will be charged.

Notice the wires that go over to the ignition switch and then to the fuse block to provide electricity to accesories.

Now lets get a green crayola and color all the parts of the charging system.

• Ignition system - Assessment

Next, the ignition system. I ask, what is the purpose of the ignition system? Spark the spark plugs in the correct order. Find the spark plugs, trace the wire back to the distributor. From the distributor to the coil, from the coil to the ignition switch. These are the parts to the ignition system. Get a blue crayola and color them blue.

Now let's look at the fuse block. Notice the top two fuses. See the jumper across the left side? That means these two are both hot at the same time. Look at the second fuse down and follow the black wire to its destination. I ask, were does it go? Someone will answer, the radio. I ask, why do you think the radio is drawn in a broken line? Because it was an option.

• Accessories - Closure

Now you find the interior light circuit. Remember, it must have a power source, switch and ground.  When you have it ,color it purple.  After someone has it, I ask how many switches, and why? (Both doors turn it on.)  What is different about the switch? (Instead of push, you release to turn on.)

If your time permits, you can have them do the horn circuit, lights, backup light, or as many or few as you want.