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Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman
Figure 6.1 (a) On an analog scope, the voltage measured at the throttle position signal wire is displayed on a horizontal line at about 0.5 volt. (b) As the throttle is opened, the horizontal line representing the voltage increases.(c) At wide-open throttle (WOT), the horizontal line indicates about 4.5 volts.
Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman
Figure 6.2 The display on a digital storage oscilloscope (DSO) displays the entire waveform from idle to wide-open throttle and then returns to idle. The display also indicates the maximum (4.72 V) and the minimum (680 mV or 0.68 V) reading. The display does not show anything until the throttle is opened, because the scope has been set up to only start displaying a waveform after a certain voltage level has been reached. This voltage is called the trigger. (Courtesy of Fluke Corporation)
Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman
Figure 6.3 An automotive oscilloscope (scope) is of the same construction as a cathode ray tube (CRT) or television screen. An automotive oscilloscope is a visual voltmeter. The higher up a trace (line) on the scope,the higher the voltage. The scope illustrates time from left to right. The longer the horizontal line, the longer the amount of time.
Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman
Figure 6.4 A pulse train in any electrical signal that turns on and off,or goes high and low in a series of pulses. Igniter and fuel injector pulses are examples of a pulse train signal. (Courtesy of Fluke Corporation)
Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman
Figure 6.5b A meter display indicating the on-time duty cycle in percent (%). Note the trigger and negative (–) symbol. This indicates that the meter started to record the percentage of on-time when the voltage dropped (start of on-time). (Courtesy of Fluke Corporation)
Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman
Figure 6.8 Battery voltage is represented by a flat horizontal line. In this example, the engine was started and the battery voltage dropped to about 10 V as shown on the left side of the scope display. When the engine started, the generator (alternator) started to charge the battery and the voltage is shown as climbing. (Courtesy of Fluke Corporation)
Advanced Engine Performance Diagnosis, Fourth EditionJames D. Halderman