Page 28 - Foton Workshop Manual - Tunland (AT)

01-22 INTRODUCTION - HOW TO TROUBLESHOOT

01 Simultaneous Symptom Test

NOTICE

• For troubleshooting, the most difficult situation is no symptom at all. In such
case, it is important to thoroughly analyze the defect described by the customer
and simulate the vehicle and circumstance upon the defect. Regardless of
experience and skill, if a service professional fails to verify the symptom during
troubleshooting, he may ignore some important messages and make the wrong
guess, which leads to ineffectiveness.
• For example, the defects occurred at cool state or due to bumpy road in driving
can never be identified when the engine is hot or the vehicle is parked. Since
vibration, heat and water leakage (humidity) are frequent causes of defects,
which are hard to reduplicate, simultaneous symptom test is introduced, which
effectively simulates the circumstance for diagnostics when the vehicle is parked.
• Key points of simultaneous symptom test: (1) First of all, confirm the symptom
and identify the position or part of the defect.To do this, before the simulation,
connect the analyzer first and narrow down the troubleshooting scope depending
on the symptom. (2) Perform the simulation symptom test, determine whether
the tested circuit is broken or working, and also verify the symptom. Refere to
the system defect lists and narrow down the scope of possible causes.

1 . Swinging - for defects potentially caused
by vibration.
(a) Part and sensor.
• Slightly swing the potentially defective
sensor with your finger and notice the
defect.
NOTICE

If too much force is imposed, it may break the
relay circuit.

(b) Connector.
• Slightly swing the connector vertically
and horizontally.
(c) Harness.

• Slightly swing the harness vertically
and horizontally. Carefully check the
connection between the harness and
the connector.

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