Installation Manual

Electrical & Electronic Application And Installation Manual
Production Release Version 1.0
Page 36
4.3.1 Important Voltage Supply Circuit Considerations
Poorly designed or installed ECM supply circuitry can lead to intermittent
engine problems and reduce the engine ECM’s ability to maintain optimum
performance under harsh conditions.
To ensure that the integrity of the electrical supply circuit is not compromised
during design and installation the following recommendations should be
adhered to.
• Supply cable wire gauge or CSA must be capable of meeting the
maximum electrical requirement demanded by the engine ECM under
all conditions.
• When specifying ECM circuit supply and return cables, which are to be
routed around hot components or form part of a machine wiring
harness bundle the appropriate cable current carrying capacity derate
should be applied.
• All ECM power pins must be connected to the main battery supply to
ensure a complete and robust electrical circuit is made.
• When splicing the ECM supply or return cables the main supply cable
must be rated to carry the total circuit current to the ECM and provide
the correct amount of mechanical durability for the number of splices
made.
• The total ECM circuit resistance must meet the stated limits (50mOhms
for 12V and 100mOhms for 24V systems) to ensure that voltage drop
across these cables is minimized.
It should also be noted that the ECM supply circuit must be routed directly
back to the application battery to maintained optimum system performance
under all conditions. Failure to do so will lead to excessive system voltage
drop and high circuit resistance as well as increased levels of supply circuit
noise.
4.3.2 Battery (+) Connection
The ECM requires three un-switched battery positive inputs; the inputs should
be permanently connected to the machine battery. When the ignition key
switch is off the ECM is in a sleep mode during which it draws a very small
residual current through the three battery connections. When the ignition key
switch is turned on the ECM will become active. It is recommended, therefore
that the ignition keyswitch is turned to the off position when connecting or
disconnecting the ECM J1 connector, to prevent large sparks which may
cause damage to the pins.
The power supply to the ECM should be taken from the battery, and not from
the starter motor terminals to avoid unnecessary system noise and voltage
drops. All 3 pins must be used.
The correct ECM voltage must be applied depending on the system voltage
specified during engine arrangement generation. The table below lists the
engine voltage dependent components.