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of joints and separator, state of the absorber (absence of cracks and
damages, serviceability of the absorber purge valve);
-operability of the evaporative emission control system (including the
absorber and the fuel tank valve). Any failure of these elements leads
to fuel supply system failures. Damaged components shall be replaced.
fuel Supply and Ignition Control System
A diagnostic connector (Fig. 9.10) is installed behind the driver's seat
at the engine right plate on the cab side for the external diagnostic system.
The control module is installed in the vehicle cab, on the right hand,
at the partition behind the driver's seat. On vehicles without partitions,
it is installed on the left strut in the cab.
Diagnostics
Functional capabilities of the engine control system and the injection
system depend on the mechanical and hydro-mechanical systems proper
functioning. Several deviations leading to faults can be mistaken for the
control system electronic part malfunctions, these are:
-low compression;
-deviation of gas distribution phases caused by incorrectly assembled
engine components;
-air ingress in the inlet pipe line;
-poor fuel quality;
-disregard of servicing periods.
The control unit is capable of diagnosing the engine control unit
components to a certain extent.
If a fault is detected, the control unit switches on the fault indication
lamp on the instrument panel with the corresponding code recorded in
the vehicle's memory.
The engine malfunction lamp switching on does not mean the engine
must be stopped immediately, since the control unit has backup modes
allowing the engine to work under conditions close to normal.
Fig. 9.10. Diagnostic connector (XS1)
