Perkins M92B, Руководство пользователя

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N37347 Chapter 3
Page 13
Engine Wiring Harness,
The engine wiring harness is designed convey information to and from the engine instrument / control panel.
Within the harness is a circuit breaker and a –ve earth fuse to protect the wiring in the event of a short circuit
as well as control relays, all of which are housed in an enclosure adjacent to the alternator.
Access to the circuit breaker is from the outside of the control box. This can be used to isolate the control
system during servicing. The 10A breaker protects the control system to the panel(s). Interruption of this will
inhibit the instrument / control panel and thus the starting of the engine.
The momentary connection of the –ve line to earth is protected by an 80A fuse located within the enclosure
adjacent to the 10A breaker.
Within the control box are 4 relays. Three are high current relays designed to control the operation of the starter
and the glowplugs. During the operation of the glowplugs a negative earth relay momentarily grounds the
engine to negative. The fourth relay controls the fuel lift pump stop solenoid and cold start advance solenoid.
In addition to monitoring the engine oil pressure and engine coolant temperature the wiring harness also
connects to a cold start advance solenoid which operates through a temperature switch which opens above
40
O
C to 50
O
C
The fuel is delivered to the fuel injection pump via an electric fuel lift pump. This commences operation in
tandem with the stop solenoid when the engine circuit switch is operated on the instrument / control panel.
Engine circuit variations due to system voltage.
12v Engines - Engines with 12v systems will have fitted a 12v to 24v inverter (Unit colour red) to operate the
24v insulated stop solenoid and 24v cold start advance solenoid.
24v Engines - Engines with 24v systems will have fitted a 24v to 12v converter (Unit colour black) to operate
the 12v fuel lift pump.
Care should be taken to ensure that there is adequate ventilation around the voltage converter / inverter to
ensure that does not overheat.
Warning!
On no account may any additional load be placed on either the inverter or converter as this may
cause the unit to fail.
Where one engine is required to charge two sets of batteries then one option is to fit a split charge relay. This
should be connected as follows:
Fit one side of the coil to the charge warning lamp terminal on the alternator. (Ind – violet cable in harness) The
other side of the coil is connected to the negative connection on the alternator.
The relay contacts are connected with one side going to the positive side of the alternator and the other side
going to the positive on the second battery. It is important to ensure that the relay and cables are of sufficient
size to handle the maximum alternator output.