●Detecting Method:
a、voltage signal method
Before testing oxygen sensor, engine must be under normal operation temperature.
【Note】Only digital voltmeter can be used to test oxygen sensor, otherwise oxygen sensor
will be damaged.
● During testing, the insulation may be pricked. Before testing, digital voltmeter leads
must be connected to oxygen sensor ground lead and signal lead. When engine idles and
under normal temperature, if air/fuel ratio has some difference with ideal air/fuel ratio, the
oxygen sensor output voltage will vary from low to high periodically. The voltage
periodically varies from 0.3V to 0.8V. After testing, apply silicon seal gum on pricked
area.
●
A continuously high voltmeter reading indicates an rich air/fuel ratio polluted oxygen
sensor ambient temperature silicon seal gum or antifreeze agent polluted oxygen sensor or
leaded fuel used in engine.
A continuously low voltmeter reading indicates an poor air/fuel ratio, sensor fault. A
medium reading maintained indicates a possible oxygen sensor fault.
● Remove oxygen sensor from engine. Connect a digital voltmeter lead to sensor, and
combust sensor sensitive element on propane welding torch flame. The propane flame could
isolate the sensitive element from oxygen, which will generate voltage. When sensitive
element is on flame, the voltage is approximately 1V, and when moved away the flame, the
voltage will drop to 0V. If sensor voltage does not change as specified, replace the oxygen
sensor.
◆Heating wire diagnostic
If the heater on sensor does not work, sensor pre-heating will be delayed, and computer
work time will also be prolonged. Then computer send a wrong rich air/fuel ratio signal,
wasting the fuel.
b、Ohmmeter method
Remove oxygen sensor and connect the ohmmeter between the heating wire and ground
wire. Referring to above diagram, if the resistance measured is not as specified, replace it
2.1.5 Speed sensor
◆ If speed sensor is damaged, the engine can not be started.
Speed sensor has 2 leads, one is signal lead (pin B7) and the other is ground wire (pin B6)
⑴ speed sensor
⑵ belt pulley with teetht
⑶ signal output
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