Download Course 2 Reference Material.indd - For Dealers

MAIN ELECTRICAL SYSTEM - 5
Main Electrical System
Engine reliability, performance and safety depend
upon an electrical system that is functioning at peek
efficiency. Marine engines are constructed from electrical
components that meet strict safety and performance
standards. These standards must be maintained to ensure
that the performance and safety features engineered into
PCM engines are not compromised.
This section covers the Main Electrical System. The
primary functions of the Main Electrical System are to
provide an uninterrupted source of constant power to
all electrical sub systems, and to crank the engine for
starting.
We will begin troubleshooting Main Electrical System
problems in the same manner we begin all of our
troubleshooting exercises, by completing the PCM
Drivability Checklist, Figure 5-1. Before you can complete
Step 4 and beyond of the PCM Drivability Checklist,
you must resolve all system power and starter issues.
Low, or no power may not only keep you from starting
the engine, but may cause the ECM to set false codes,
cause improper operation of the engine’s ignition and fuel
systems and may cause erroneous instrument readings.
We will use the following procedures to troubleshoot the
Main Electrical System.
This partial list contains some of the more common
complaints associated with the Main Electrical System:
NOTE: The discussion that follows is for current
production engines. Older models may have different
configurations and illustrations. The following may not
apply to these older models.
1. A dead battery
2. Over- or under-voltage displayed on the volt
gauge
Refer to Figure 5-2. The Main Electrical System consists
of three sub-systems.
3. Slow cranking or no crank of the engine
4. The engine cranks but will not start
1. System Power - The 12 volt Battery and its
associated components and cables.
5. The engine stops and will not restart
6. The engine stops, but will restart
2. Starter Circuit - The Starter and its associated
components and wiring.
7. The engine cuts off and on, or stalls during
operation.
3. Charge Circuit - The Alternator and its
associated components and wiring.
8. The malfunction indicator light (MIL) and/or
warning buzzer lights/sounds during cranking.
No DTC codes are stored in the ECM’s
memory.
It is necessary that a technician servicing PCM engines
maintain the reliability, performance and safety built into
our engines by:
9. Scan Tool does not recognize the ECM.
1. Repairing electrical system components in a
manner consistent with our design standards.
10. Any similar complaint that may be caused by
the loss of a power feed circuit.
2. Replacing defective components with original
equipment parts that meet all of our applicable
marine safety and manufacturer design criteria.
Warning: All PCM electrical components are certified
to meet Coast Guard requirements for ignition
or explosion protection. DO NOT use electrical
components that do not meet the Coast Guard
requirements.
Symptoms of a malfunctioning Main Electrical System may
not always be easily isolated to the Main Electrical System
itself. Many of the symptoms reported could be interpreted
as Engine Management or Fuel System problems, while
others can be directly associated with the Main Electrical
System. As shown in the procedures so far, verifying that
you have sufficient power is one of the very first steps to
perform. In all cases, whether performing the On-Board
Diagnostic System Check or troubleshooting the Fuel
System; having the correct voltage and current available is
essential for proper operation.
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