85
If anything happens
Engines with type designation DH10A have electronically
control injector pump while the THD102 engine has me-
chanically controlled injector pump. (This section does not
apply to buses with THD 102).
The DH10A control system is called EDC (Electronic Diesel
Control).
The advantages of the EDC system is its accuracy in fuel
control and that it can communicate with other electronic
control systems for various functions, e.g. ABS and ASR.
Power supply, fuses
With a fault-free power supply, the EDC control unit will
have dual safety against power cuts and the power supply
indicator light will be off. (Illustration of lamp, see next
page.)
If there is a break in the normal power supply to the control
unit, fuse 45 (10A) in the main distribution box, the lamp will
go on continuously. Current is then fed over fuse 46 (10A) in
the electrical distribution box in front of the core assembly.
The bus can be driven as normal even if the lamp comes on
but to avoid the risk of a complete power failure, which will
cause the engine to stall, we recommend allowing a Volvo
garage to rectify the fault as soon as possible.
If fuse 44 (5A) in the main distribution box has blown, it will not
be possible to adjust the idling speed and the cruise control
will not work.
(Note: fuses 44, 45 and 46 are fitted in separate holders).
The control unit receives information on:
accelerator position
bus speed
footbrake active
clutch pedal depressed (if fitted)
exhaust brake active (if fitted)
charge air pressure
charge air temperature
coolant temperature
engine speed
idle speed change
The control unit sends signals on (governs):
fuel quantity
engine shut-down
The control unit stores and displays fault codes (diagnosis).
EDC
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