Precautions On Checking Vehicle Sensor - Launch Sensorbox User Manual

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3.2.5 Precautions on checking vehicle sensor

Hold the connector when plugging or unplugging it. Do not pull the cable for
unplugging.
At first check the fuse, fusible line and terminals. Then check others after
eliminating these faults.
When measuring voltage, the ignition switch should be on and the battery
voltage should not be less than 11V.
When measuring voltage, please shake the lead lightly in the vertical and
horizontal direction for more precision.
When checking whether there is open in the line, disconnect the CEU and
the relevant sensor at first, then measure the resistance among the ports of
sensor in order to determine whether open-circuit / contact fault exists or
not.
When checking if there is a short in the line, please disconnect the CEU and
the relevant sensor, then measure the resistance value of the ports between
the connected port and the vehicle body. If the resistance value is more than
1MΩ, no fault occurs.
Before disassembling the engine electrical control system cable, cut off the
power supply, that is, turn the ignition switch OFF and disconnect the cables
on the battery poles.
Contact the test probe and the two terminals/ the two leads to be measured
when measuring the voltage between the two terminals or the two leads.
Contact the red test probe to the terminal/ the cable to be measured, and
the black probe to the ground when measuring voltage of one terminal/ one
cable.
When checking the continuity of the terminals, contacts and leads, the
method for measuring their resistances can be used.
Check the faults in the terminals of the CEU to sensors, relays, etc.
There are two test probes in the testing wire. The black one is the common
signal terminal (signal GND); the red one is the input terminal for voltage,
resistance, and frequency test and output terminal for simulation voltage,
simulation frequency and oxygen sensor. Please choose the correct probes
to match the different terminals.
X-431 PAD Sensorbox User's Manual
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