Suzuki outboard motors 1988 2003 repair manual., Page 116Get this manual
5-4 IGNITION AND ELECTRICAL SYSTEMS WIRINGHARNESSES
The average vessel contains miles of wiring, with hundreds of individual connectionsTo protect the many wires from damage and to keep them from becoming confusing tangle, they are organized into bundles, enclosed in plastic or taped together and called wiring harnessesDifferent harnesses serve different parts of the vesselIndividual wires are color coded to help trace them through harness where sections are hidden from viewMarine wiring or circuit conductors can be either single strand wire, multistrand wire or printed circuitrySingle strand wire has solid metal core and is usually used inside such components as alternators, motors, relays and other devicesMulti-strand wire has core made of many small strands of wire twisted together into single conductorMost of the wiring in marine electrical system is made up of multi-strand wire, either as single conductor or grouped together in harnessAll wiring is color coded on the insulator, either as solid color or as colored wire with an identification stripeA printed circuit is thin film of copper or other conductor that is printed on an insulator backingOccasionally, printed circuit is sandwiched between two sheets of plastic for more protection and flexibilityA complete printed circuit, consisting of conductors, insulating material and connectors is called printed circuit boardPrinted circuitry is used in place of individual wires or harnesses in places where space is limited, such as behind instrument panelsSince marine electrical systems are very sensitive to changes in resistance, the selection of properly sized wires is critical when systems are repairedA loose or corroded connection or replacement wire that is too small for the circuit will add extra resistance and an additional voltage drop to the circuitThe wire gauge number is an expression of the cross-section area of the conductorVessels from countries that use the metric system will typically describe the wire size as its cross-sectional area in square millimetersIn this method, the larger the wire, the greater the numberAnother common system for expressing wire size is the American Wire Gauge (AWG) system, As gauge number increases, area decreases and the wire becomes smallerAn I8 gauge wire is smaller than gauge wireA wire with higher gauge number will carry less current than wire with lower gauge number, Gauge wire size refers to the size of the strands of the conductor, not the size of the complete wire with insulatorIt is possible, therefore, to have two wires of the same gauge with different diameters because one may have thicker insulation than the otherIt is essential to understand how circuit works before trying to figure out why it doesn'tAn electrical schematic shows the electrical current paths when circuit is operating properlySchematics break the entire electrical system down into individual circuitsIn schematic, usually no attempt is made to represent wiring and components as they physically appear on the vessel; switches and other components are shown as simply as possible, Face views of harness connectors show the cavity or terminal locations in all multi-pin connectors to help locate test pointsconnector is exposed to the elementsTerminals are protected against moisture and dirt by sealing rings which provide weather tight sealAll repairs require the use of special terminal and the tool required to service itUnlike standard blade type terminals, these weatherproof terminals cannot be straightened once they are bentMake certain that the connectors are properly seated and all of the sealing rings are in place when connecting leadsMolded-these connectors require complete replacement of the connector if found to be defectiveThis means splicing new connector assembly into the harnessAll splices should be soldered to insure proper contactUse care when probing the connections or replacing terminals in them, as it is possible to create short circuit between opposite terminals, If this happens to the wrong terminal pair, it is possible to damage certain componentsAlways use jumper wires between connectors for circuit checking and NEVER probe through weatherproof seals, Hard Shell-unlike molded connectors, the terminal contacts in hardshell connectors can be replaced, Replacement usually involves the use of special terminal removal tool that depresses the locking tangs (barbs) on the connector terminal and allows the connector to be removed from the rear of the shellThe connector shell should be replaced if it shows any evidence of burning, melting, cracks, or breaksReplace individual terminals that are burnt, corrodeddistorted or loosePinpointing the exact cause of trouble in an electrical circuit is most times accomplished by the use of special test equipmentThe following sections describe different types of commonly used test equipment and briefly explain how to use them in diagnosis, In addition to the information covered below, the tool manufacturer's instruction manual (provided with most tools) should be read and clearly understood before attempting any test proceduresJUMPER WIRES