x Features of the Textbook The instructional design of this textbook includes student-focused learning tools to help you succeed. This visual guide highlights these features. Chapter Opening Materials Each chapter opening contains a list of learning objectives and a list of technical terms. Objectives clearly identify the knowl- edge and skills to be gained when the chapter is completed. Technical Terms list the key words to be learned in the chapter. Additional Features Additional features are used throughout the body of each chapter to further learning and knowledge. Warnings alert you to potentially dangerous materials and practices. Cautions alert you to practices that could potentially damage equipment or instruments. Notes provide advice and guidance that is especially applicable for on-the-job situations. Working Smart features contain tips for performing collision repair and refinishing procedures more efficiently. Working Green notes high- light key items related to sustainability, energy efficiency, and environmental issues. Illustrations Illustrations have been designed to clearly and simply communicate the specific topic. Illustrations have been updated for this edition. Many of the photographic images have been updated to show the latest equipment. Copyright Goodheart-Willcox Co., Inc. 59 Objectives After studying this chapter, you will be able to: • Describe the various factors that will influence the way a vehicle will react in a collision. • Identify bends, body lines, and crowns. • Differentiate between direct and indirect damage. • Explain the bend-versus-kink rule. • Describe the types of collision damage found on full-frame and unibody vehicles. inertia damage kickup kink lateral force longitudinal force mash plastic deformation plasticity sag sidesway simple rolled buckles surface area of impact target twist upset vehicle height work hardening yield point C H A P T E R 4 arrowhead bend bend-versus-kink rule body line buckle collapsed-hinge buckle combination crown crown dent diamond direct damage elastic deformation elasticity force grains impact angle indirect damage inertia Technical Terms Fundamentals of Collision Damage 511 Chapter 20 Electrical System Copyright Goodheart-Willcox Co., Inc. diagnostic trouble code (DTC) that will be recorded in the vehicle diagnostic system. These DTCs can be accessed, interpreted, and cleared with a scan tool. The scan tool is plugged into the diagnostic port in the lower part of the driver’s side instrument panel. Before repairs begin, a pre-repair scan is performed to identify any DTCs that must be addressed during the repair process. Operations during the repair process, such as disconnecting the battery, may generate a DTC. A post scan is performed after the vehicle repairs are complete. This check will assure the customer and body shop that all collision- related problems have been fixed. Both collision- related DTCs that have been corrected and DTCs generated during the repair process can be cleared during the scanning operation. DTCs unrelated to the repair, such as a malfunctioning oxygen sensor, should be reported to the customer. Electrical System Service Few things are as frustrating as finding and repairing an automotive electrical problem. The key is having a logical and systematic plan. The following are basic procedures used in testing and replacing elec- trical components. Battery and Alternator Service The vehicle’s clock, radio, and computers may all have memory that is maintained by battery power. Disconnecting the battery wipes out the memory on these devices. To avoid this problem, a memory saver can be connected to the vehicle’s lighter or auxiliary 12-volt outlet before the battery is discon- nected. A 9-volt battery in the memory saver maintains the memory while the vehicle’s 12-volt battery is disconnected. A battery can be damaged in a collision. Figure 20-33 shows the most common of battery damage—a cracked case. A cracked battery case cannot be repaired. If a crack is present, the battery must be replaced. Batteries also wear out. A worn-out battery will not hold a charge.. Always wear safety glasses when connecting or working on a battery. Do not create sparks. A battery produces hydrogen gas. This gas can explode if a spark is created near the battery. The resulting explosion may cause battery case to shatter, injuring anyone in the way. NOTE WARNING A dirty battery should be cleaned. A mixture of baking soda and water can be used to clean the battery terminals and the case. The baking soda neutralizes battery acid. Corrosion on the terminals can be removed with a wire brush. Battery cables can also corrode and deteriorate with age. Replace loose or corroded cables by unbolting the cable and installing a new one. Dead batteries are common in body shops. When charging a battery to start a vehicle, first determine the type of battery. Select the correct charger for the battery, then hook up the battery charger to the battery terminals and set the battery charger for 40–60 amps. Turn on the charger and allow the battery to charge for a maximum of 30 minutes. Then, disconnect the charger and start the vehicle. Batteries that are not recycled end up in landfills where they can leak toxic materials into the environment. The EPA states that 90% of automotive batteries are To a vehicle, use the sequence shown Figure 20-34. First, clamp one end of the red cable to the positive terminal of the dead battery. Then, clamp the other end of the red cable to the positive terminal of the good battery. Next, connect one end of the black cable to the negative terminal of the good battery. Finally, connect the other end of the black cable to the engine block or frame of the vehicle with the dead battery. Start the vehicle with the dead battery and disconnect the wires in the reverse order of installation.. On a front-wheel-drive vehicle, a side impact on the right front corner of the vehicle may the WORKING GREEN Goodheart-Willcox Publisher Figure 20-33. The force of a collision cracked this battery case. t- lco ws ttype y f y ked ked b ed. y d. B ies al ld ge s gAs g r g ery gen gcomponents g x i ting explosion t e badhesive j ing i t e f recrecycled. jjump-start iin Fi cla f y. f g f y, f f y. rt b f n im act ri ht f f e 277 Chapter 12 Plastic Repair Copyright Goodheart-Willcox Co., Inc. adhesive is shown in Figure 12-12. With this adhe- sive, an applicator gun and a tube are the applicator gun is triggered, the two compo- nents are forced together in the mixing tube. By the time the reach the end of the tube, they are thoroughly mixed. However, you should discard the first 2″the of because it may not be prop- erly mixed. The adhesive is applied to the damaged area directly from the tube. Adhesives can be used to fill gouges or to attach reinforcements. Plastic repair materials are available from a number of different vendors. Each vendor provides written guidelines for the use of its product. Always read the vendor’s guidelines before beginning the repair. Always follow the vendor’s guidelines, even if they deviate from the instructions given in this chapter. Adhesion Promoter A spray adhesion promoter is shown in Figure 12-13. This chemical is used before applying adhesives to olefin-containing plastics. The adhesion promoter changes the chemistry of the olefin plastic surface, allowing adhesives to stick. Adhesion promoter may also be applied with a brush or dauber. The adhe- sive promoter must be applied before the adhesive. Sanding will remove the layer of adhesion promoter. If the adhesive is sanded but more adhesive is required to fill, additional adhesion promoter must be applied to the repair area. WORKING SMART Some flexible plastic repair materials are made premixed with the material. A separate adhesion promoter is not required. These types of plastic repair materials will adhere to any flex- ible plastic. Meshmove Mesh is used as reinforcement when making plastic repairs. Plastic and metal mesh is shown in Figure 12-14. The steel mesh can be melted into the plastic when welding. It strengthens the repair area. A plastic mesh can be used with adhesives, again strengthening the repaired area. The plastic mesh is laid down and the adhesive is applied over it. Goodheart-Willcox Publisher Figure 12-14. A—Plastic mesh. B—Aluminum mesh. A B Goodheart-Willcox Publisher Figure 12-13. Adhesion promoter allows repair material to adhere to plastic. Goodheart-Willcox Publisher Figure 12-12. A mixing tube combines the two adhesive components. The two separate components enter the tube and they are combined into a uniform mixture by the spirals in the tube.