Suzuki outboard motors 1988 2003 repair manual., Page 118Get this manual
5-6 IGNITION AND ELECTRICAL SYSTEMS megohms or more)A brief description of the multimeter main test functions follows: Voltmeter-the voltmeter is used to measure voltage at any point in circuit, or to measure the voltage drop across any part of circuitVoltmeters usually have various scales and selector switch to allow the reading of different voltage rangesThe voltmeter has positive and negative leadTo avoid damage to the meter, always connect the negative lead to the negative (-) side of the circuit (to ground or nearest the ground side of the circuit) and connect the positive lead to the positive (+) side of the circuit (to the power source or the nearest power source)Note that the negative voltmeter lead will always be black and that the positive voltmeter will always be some color other than black (usually red)Ohmmeter-the ohmmeter is designed to read resistance (measured in ohms) in circuit or componentMost ohmmeters will have selector switch which permits the measurement of different ranges of resistance (usually the tematic checks will often turn up most causes on the first inspection, without wasting time checking components that have little or no relationship to the problemTest all repairs after the work is done to make sure that the problem is fixedSome causes can be traced to more than one component, so careful verification of repair work is important in order to pick up additional malfunctions that may cause problem to reappear or different problem to ariseA blown fuse, for example, is simple problem that may require more than another fuse to repairIf you don't look for problem that caused fuse to blow, shorted wire (for example) may go undetectedExperience has illustrated that most problems tend to be the result of fairly simple and obvious cause, such as loose or corroded connectors, bad grounds or damaged wire insulation which causes shortThis makes careful visual inspection of components during testing essential to quick and accurate troubleshootingbattery, the ohmmeter can be used like self-powered test lightwhen the ohmmeter is connected, current from the ohmmeter flows through the circuit or component being testedSince the ohmmeter's internal resistance and voltage are known values, the amount of current flow through the meter depends on the resistance of the circuit or component being testedThe ohmmeter can also be used to perform continuity test for suspected open circuitsIn using the meter for making continuity checks, do not be concerned with the actual resistance readingsZero resistance, or any ohm reading, indicates continuity in the circuitInfinite resistance indicates an opening in the circuitA high resistance reading where there should be none indicates problem in the circuitChecks for short circuits are made in the same manner as checks for open circuits, except that the circuit must be isolated from both power and normal groundInfinite resistance indicates no continuity, while zero resistance indicates dead shortVOLTAGE
This test determines voltage available from the battery and should be the first step in any electrical troubleshooting procedure after visual inspectionMany electrical problems, especially on electronically controlled systems, can be caused by low state of charge in the batteryExcessive corrosion at the battery cable terminals can cause poor contact that will prevent proper charging and full battery current flow1Set the voltmeter selector switch to the 20V position2Connect the multimeter negative lead to the battery's negative (-) post or terminal and the positive lead to the battery's positive (+) post or terminal3Turn the ignition switch ON to provide load4A well charaed batterv should reaister over 12 voltsIf the meter reads below 11.5 volts, ?he battery power may be insufficient to operate the electrical system properlyNever use an ohmmeter to check the resistance of component or wire while there is voltage applied to the circuit Ammeter-an ammeter measures the amount of current flowing through circuit in units called amperes or amps At normal operating voltage, most circuits have characteristic amount of amperes, called "current draw" which can be measured using an ammeter By referring to specified current draw rating, then measuring the amperes and comparing the two values, one can determine what is happening within the circuit to aid in diagnosis An open circuit, for example, will not allow any current to flow, so the ammeter reading will be zero damaged component or circuit will have an increased current draw, so the reading will be high The ammeter is always connected in series with the circuit being tested All of the current that normally flows through the circuit must also flow through the ammeter, if there is any other path for the current to follow, the ammeter reading will not be accurate The ammeter itself has very little resistance to current flow and, therefore, will not affect the circuit, but it will measure current draw only when the circuit is closed and electricity is flowing Excessive current draw can blow fuses and drain the battery, while reduced current draw can cause motors to run slowly, lights to dim and other components to not operate properly