User's Manual

LAUNCH X-431Tool User’s Manual
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connected to ECU because most ECU’s are
operated under low voltage (about 5V).
Whenever you work in the vicinity of ECU or
engine control system, please obey the
following precautions:
1. Never damage the lead or connector.
Prevent them from being grounded or
contacting with an unexpected power source.
2. Never use the electrical test tool that is
powered by 6V battery or over. Strong
current may cause the element in ECU
broken or shorted. For checking the engine
control circuit, only the multimeter with large
internal impedance (over 10MΩ) can be
used.
3. Never try to disassemble or repair ECU if
there are not necessary tools and
information. Any mistake may damage the
component or increase the difficulty for
service station.
4. The spark plug wire must be at least 25.4mm
from any sensor circuit or control circuit.
Some unexpected fault in ECU circuit is
caused by magnetic fields that transmit
wrong signal to ECU. High tension wire or
transformer may interfere with ECU, but the
most common cause for such problem is that
the spark plug is too close to ECU harness.
5. Be careful when moving ECU or working
around ECU. Remember that static electricity
may cause strong electrical shock and
damage ECU.