Section 2 Using the Electrical Wiring Diagram

1 Body Electrical Diagnosis - Course L65211. Introduce the features of each EWD Explain how to use the System Circuit Diagram3. Explain how the System Circuit Diagram works with theadditional support sections in the Show how to apply the System Circuit diagrams and supportsections in the diagnostic process5. Explain and practice the process of tracing current flow in 2 Using the Electrical Wiring DiagramLearning Objectives: Section 22 LEXUS Technical TrainingUsing the Electrical Wiring DiagramBody Electrical Diagnosis - Course L6523 One of the keys to a quick and successful Electrical diagnosis is correctlyusing the Lexus Electrical Wiring Diagram or EWD.

2 The EWD isnot just a book of Wiring diagrams , but an information resource foranything Electrical on the vehicle. Everything from connector ID andlocation to what circuits share splice points is included in this there is so much information, it takes a little practice to learnwhere it is located, and what each of the EWD symbols and individualsections can tell you. We will take a detailed look at all of thesefeatures, and how to use them in diagnosing an Electrical you follow your instructor's tour" of the EWD Sections, it isrecommended that you use the actual EWD, instead of thisTechnician Handbook.

3 This way, you will be getting a feel" for theactual tool that you have at your the EWD(Through 1998 MY)The EWD is an invaluabletool when diagnosingan Electrical where specificinformation is, and the system that the bookuses helps to speed upthe diagnostic 24 LEXUS Technical TrainingSectionsof the EWD(Starting 2000 MY)Starting in the 2000 ModelYear, the EWD sectionshave been rearranged andsome new sections havebeen the large number of pages and sections in the EWD, the fastestway to find the Wiring Diagram or information you need is to use theTable of are two table of contents that are available.

4 One is on the titlepage of the book. This lists all of the sections (1998 MY = A-K;2000 MY = A-M) and also has an alphabetical list of all the SystemCircuit diagrams located in Section I. These Wiring diagrams are the heart" of the EWD, and the place to start when diagnosing anelectrical problem. There is also a listing of each System CircuitDiagram on the first page of Section Table ofContentsUsing the Electrical Wiring DiagramBody Electrical Diagnosis - Course L6525 Table ofContentsThe Table of Contents isfound on the title page ofthe EWD. A second tableof contents for just theSystem Circuit Diagramsis found at the beginningof Section I ( Section Hstarting with 1999 MY).

5 Section 26 LEXUS Technical TrainingThe EWD is built around the use of the System Circuit diagrams ( Section I through 1998 MY, Section H starting with 1999 MY). Thesewiring diagrams provide circuit road maps" for individual circuits orsystems on the vehicle. You'll find that there are a lot of advantages tousing this type of Diagram over the old-style" overall Wiring diagrams . More InformationThere is a lot of written information (such as component IDs) oneach Diagram that works with the support materials/otherSections in the manual. Also, the symbols that are usedgraphically give you information about components, connectors, orwires.

6 Understanding the full meaning of the symbols and IDcallouts" will save you time when trying to locate or identify thesecomponents on the car. Easier to UseEvery Diagram shows only one system at a time. The parallelconnections to other circuits can be traced Using Power Source andGround Point sections. Tracing current flow through the circuit isalso easier because the power is at the top and the ground is atthe bottom of each page. Printed in ColorBecause the diagrams are printed in color, identifying the wiresshown on the Wiring Diagram in the vehicle harness or at theconnectors is a lot DiagramsThe entire EWD is builtaround the System CircuitDiagram.

7 Every number,letter, shape, and shadingon the Diagram tells youinformation that can helpyou to locate or identifycomponents on thecar ISystem CircuitDiagramsAdvantagesUsing the Electrical Wiring DiagramBody Electrical Diagnosis - Course L6527 Watch forAsterisks*,(Parenthesis),and the Title atthe TopThese small notes willmake a big difference!These marks alert you todifferent Wiring orconnections based uponmodel, engine type,California, Federal, orCanadian specificationsSection 28 LEXUS Technical TrainingOn each System Circuit Diagram , there is a lot of information thatis given to you through the use of different symbols, colors, numbers,and letters.

8 Understanding the meaning behind each of these is veryimportant to effectively use the being shown in color, wire colors are also indicated by analphabetical code next to each of the wires. The first letter representsthe basic wire color, and the second letter indicates the color of the stripe" on the wire. Blue WiresAs you look at the list below, note that the color blue is presented bythe letter L" to separate it from the letter B" used to identify black".Also note that there is no light blue" wire designation used in Lexuswiring harnesses. If it is any shade of blue, its considered blue (L).

9 Component Pigtails"The wire colors of component pigtails" (such as on an igniter) arenot shown in the EWD. The colors in the EWD represent thevehicle harness up to where it is connected to the component. Silver Bands on the Wire InsulationOn some wires you will find small silver bands". These bands (whichare not shown on the Wiring Diagram ) indicate that the wire uses aPVC insulation. This insulation is lighter in weight and thinnerthan the normal insulation, making the wire diameter appear smallerthan it actually is. (May look like a 20 ga. wire on the outside, but isreally a 16 ga. when the wire strands are examined)Wire IdentificationWires are identified bycolor and by the lettersnext to the wire.

10 The letterthat follows the - is thestripe on the wire. Notethat the color BLUE isrepresented by theletter L .B= BlackBR = BrownG= GreenGR = GreyL= BlueLG = Light GreenY= YellowSB = Sky BlueO= OrangeP= PinkR= RedV= VioletW= WhiteUnderstandingthe SystemCircuitDiagramWire ColorsUsing the Electrical Wiring DiagramBody Electrical Diagnosis - Course L6529 Junction blocks are used to distribute power and ground to thedifferent circuits. A junction block joins the circuits Using layers ofinsulated, solid metal plates, eliminating the need for many additionalsplices, and improving reliability.