Page 68 - Foton Workshop Manual - Auman EST-M

DI - 14 Diagnosis - Diagnosis-fault diagnosis of electronic and electrical parts

Warning
● Don’t spray water on the engine directly but the front of heat radiator to change the temperature and
humidity indirectly.

● Don’t spray water on electronic elements directly.
● Take special care when the the leaked vehicle sprays water, because the leaked water may damage
ECM.
4. Full electric connection method

a. When the fault may be caused by overhigh electric load, test all the electric loads (including heater blower,
headlamp and rear windscreen defroster) to check whether the fault occurs.
b. In the simulated test of fault symptom, it’s required to find out the faulty position or part while confirming
the fault symptom. In order to do so, reduce the circuit range possible to cause the fault as per the fault
symptoms before testing and pre-connecting the tester, and then perform the simulated test of fault symptom
to judge whether the tested circuit is normal.

c. In case of meeting any exceptional fault, make full use of fault remedy method and DTC list to analyze and
diagnose the fault, so as to reduce the fault range and find out the faulty position quickly. This method is very
practical and effective.
5. Diagnostic unit freeze data flow method

Adopt the captured data flow function of diagnostic unit. In case of reading the data flow of diagnostic unit,
simulate the fault state as per the fault freeze data recorded by diagnostic unit.
6. Oscilloscope method

Capture the waveform with an oscilloscope to assist in finding out intermittent faults.
7. Other methods
Part replacement method: before replacing ECM or other control modules, diagnose other external causes
sufficiently, because the control module is an expensive high-reliability product.
Warning

In case of checking and replacing the control unit with possible damages, install the possibly damaged
control unit onto the faultless vehicle for testing, and don’t install a new control unit on the faulty
vehicle for testing, otherwise the control unit may be damaged.
Basic inspection

When the fault can’t be confirmed through DTC check, analyze the fault remedy of all the circuits possible to
cause the faults. In many cases, the positions causing the faults can be quickly and effectively found out by
performing the basic engine check shown in the following flow chart. Therefore, it’s very necessary to adopt
this checking method during the removal of engine faults.
1. Check the battery voltage
Warning

When the engine stops or the ignition switch is at LOCK, perform this inspection

DI-014