Repair wiring harness
Lesson Plan for
AUT 186-187/AUT 292
Automotive Service Technology Section C/Automotive Special Problems
Course HS Title: / Automobile Service Technology/Special Problems / Program:KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
Introduction/Context / This lesson will instruct the student on how to repair a wiring harness, 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 an Automotive 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
Repair wiring harness.
No. / Objective
1 / Given the proper tools and instruction, the student will be able to repair a wiring harness, 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
Common Core Technical Standards:
TD-SYS-2
New Common Core Standards:
RST 11-12.2
RST 11-12 3
INSTRUCTIONAL MATERIALS/TECHNOLOGY
Textbooks and Workbooks
Author / Title/ISBN No. / Edition / Publisher / PagesJames E. Duffy / Auto Electricity and Electronics / Goodheart-Wilcox Company / 90-102
Supplies
5 pack / Heat shrink tubing
6 Rolls / Solder
12 Rolls / Tape (Electrical)
1 / Wire Connector Set
Equipment
1 / Heat Gun
1 / Multipurpose Electrical Pliers
1 / Side Cutting Pliers
1 / Soldering Gun
1 / Soldering Iron
1 / Soldering Torch
1 / Terminal Pliers
Content/Presentation/Demonstration Outline
Instruct students on the importance of making proper wiring repairs. Vehicles may have over several hundred feet of wiring. With these wires, there are many connectors and wires that fail under stress and vibration. This can create high resistance problems that must be properly repaired.To instruct students on the proper wiring and connector repair, the students must first understand how to identify the different types of wires and sizes. First, explain the difference in solid and stranded wires. Solid wires have a single conductor in its insulation. Stranded wires have numerous wires in its insulation.
Wire size is determined by the diameter of the conductor; explain the difference between the AWG and the Metric wire gauge sizes. AWG is the abbreviation for American Wire Gauge. The AWG wire has a number to identify its diameter. The smaller the number, the larger diameter wire. The Metric system is just the opposite. The diameter of the wire uses a number, but the smaller diameter wires have a smaller number. It is important to explain to the students the importance of using the correct diameter wire when making a repair. Using too small of a diameter wire can cause a high resistance in the circuit.
Explain how to properly cut and strip wires. Cutting the wires can be done with either side-cut pliers or multipurpose electrical pliers. Make sure to cut completely through the wire. If not, you may have uneven wires that can become a problem when making the repair. Only strip wires with wire strippers. Select the hole that corresponds to the wire diameter that you are cutting. If you put a larger diameter wire in a smaller hole, it could strip some of the wires away with the insulation.
Instruct students on the proper procedure for installing wire terminals and connectors. There are many styles and types of wire terminals and connectors. To use them, the insulation of the wire must be stripped as previously described. After stripping the insulation back, twist the wire conductor to fit inside the wire terminal or connector. Have students use the multipurpose electrical pliers and crimp the connector. Do not crimp the plastic part of the connector! Crimp the metal tab where the wires are fed through. After crimping the connector, pull on the wire to ensure the crimp was successful.
Instruct students on the proper methods of soldering. Soldering is one of the best methods for securing a wiring repair. Explain to the students the different types of soldering methods. Soldering guns are one of the best soldering methods. They heat up quicker taking less time. The pencil-type soldering iron is smaller and takes more time to heat up but can be used in places where space is a problem. The torch is a quick method for soldering, but has limited uses around flammable materials.
Explain the difference in solder. Acid-core solder cannot be used when making repairs on automotive wiring due to the acid being corrosive. Rosin-core solder must be used on any automotive wiring repair. To make a repair by soldering, strip the insulation from the conductor. If reattaching two wires together, strip both ends, push wires together, and twist the conductor. Heat the conductor with the soldering tool of choice until the conductor is hot enough to melt the solder. Do not melt the solder with the tool after the solder has thoroughly melted into the repair. Let stand until cool to the touch.
If two wires were joined in the repair, use a piece of heat shrink. Prior to the repair, use a piece just large enough so it can slide over the repaired area. When finished with the soldering repair, wait until the solder cools, then slide the heat shrink over the repair and use a heat gun to heat the shrink tubing. This will make a durable repair and apply a new coat of insulation to the wiring.
Explain how to repair factory connectors. Factory connectors can cause problems by pushing the wire out the back of the connector. They can be damaged by negligence when reconnecting two connectors by spreading the terminals and bending pins. Sometimes terminal replacement is necessary. Most factory terminals must have the necessary tools to remove them from their housing. They also require the use of special crimp tools to install the new terminals.
Most terminals are considered a push-type or pull-type terminal, meaning they either lock into place by pushing the wire into the housing, or by installing the wire through the housing, installing the new terminal, and then pulling it back through the housing. To make a repair to a terminal, you must first release it from the housing. First, determine the type of terminal you have, then using a release tool, release the terminal from the housing. Cut the damaged terminal from the wire and strip back the insulation. Next, insert the conductor into the new terminal, and using the special crimp tool, crimp the terminal. Some, if not most, factory connectors have a seal to keep out the moisture and dirt.
Explain how to repair fusible links. Fusible links protect major circuits in automotive wiring system. If a fusible link burns up, find the fault before making the repair. A fusible link is usually four times smaller in diameter than the circuit it protects. To replace the fusible link, cut out the old burned up link and strip the insulation back on each end. Obtain a pair of butt-splice connectors and solder in the ends of the link. After time is allowed for cooling, apply electrical tape to protect the repair. After the repair has been made, recheck the circuit.
Applications/Practice
Evaluation and feedback Prior to Testing or Lab Work
STUDENT ASSESSMENT:(Assess student progress with performance criteria.)
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.)