Installation Manual

Electrical & Electronic Application And Installation Manual
Production Release Version 1.0
Page 30
4.0 Power & Grounding Considerations
4.1 System Grounding
Although the engine electronics are all directly grounded via the ECM
connector, it is also necessary to ensure that the engine block is properly
grounded, to provide a good return path for components such as the starter
motor, alternator and cold start aids.
Improper grounding results in unreliable electrical circuit paths. Stray
electrical currents can damage mechanical components and make electronic
systems prone to interference. These problems are often very difficult to
diagnose and repair.
4.1.1 Ground Stud On Starter Motor
If the Starter motor has a grounding stud then this should be used. The
ground connection should be made directly back to the battery negative
terminal.
The starter motor ground path must not include any flanges or joints. Painted
surfaces and flexible mounts in particular must be avoided. Star washers must
not be relied upon to make contact though paint.
The ground cable should be of sufficient cross sectional area to ensure that
the total starter motor supply circuit resistance does not exceed 1.7mOhms for
a 12V system and 3.4mOhm for a 24V system.
Please refer to the Starting and Charging Systems Manual for further
information on starter motor, alternator, battery and complete system
installation guidelines.
4.1.2 Engine Block Ground Connection
A separate engine block ground should be used in addition to the starter
motor ground. A ground cable direct from the battery negative or starter
ground terminal should be connected to a ring terminal, which connects to one
of the two tapping’s shown in figures 4.1 and 4.2. The tapped holes will be
reserved for customer use and can be used for grounding purposes.
If a tapping is used it should be checked to ensure it is free from lacquer, paint
and dirt before the connection is made. An M10 metric screw plated with zinc
should be used. A washer should retain the ring terminal and the screw
tightened to 44Nm (32 lb-ft).