Page 31 - Foton Workshop Manual - Sauvana

INTRODUCTION - HOW TO TROUBLESHOOT THE VEHICLE 01-25
SIMULATING DETECTION FOR SYMPTOM

NOTICE:
• As for troubleshooting, the most difficult is that there is no symptom being found. In this
case, intensively analyze the faults mentioned by clients, and simulate the vehicle and the 01
environmental condition while the faults appear. For a maintenance technician, regardless
of his abundant experience and skillful technique, if he do not identify the symptom in
troubleshooting, he must neglect some important information in maintenance operations
and make wrong guessworks.
• For example, those faults, which only exist when the engine is cold or when the highway
conditions are poor in the process of moving, will never be found when the engine is hot
or when the vehicle stops. Common causes for faults such as vibration, high temperature,
water leakage (dampness), etc., can hardly appear again. Therefore, we introduce the
simulating detection for symptom here, which is an effective method to modulate the
external factors while the vehicle is at parking state.
• Key points on the simulating detection for symptom:
Firstly, the symptom must be identified and the position or part must be detected. To
achieve this goal, before the simulating detection for symptom, connect the diagnostic
device firstly and decrease the checking scope of the malfunctioning circuit according
to the symptom. Then, implement the simulating detection for symptom to decide
whether the circuit tested is out of order or in good condition and meanwhile to ensure
the symptom. Inquire all the system symptom table to decrease the scope of the possible
causes for the symptom.

1. Shake method—is for the faults possibly
caused by vibration
(a). Parts and sensors
• Shake slightly the sensor, which may
have faults, and check whether there are
faults.
WARNING:
Shaking at full tilt may lead to the the short circuit
of the relay.
(b). Connector.
• Shake the connector slightly in vertical
and horizontal directions.
(c). Harness.
• Shake the harness slightly in vertical
and horizontal directions. The main area
for checking is the connection between
harness and connector.

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