SERVICE MANUAL NUMBER 24
FUEL INJECTION DESCRIPTIONS AND SYSTEM OPERATION
Reading Codes
The provision for communicating with the ECM is the Data Link Connector (DLC) connector.
It is part of the EFI engine wiring harness, and is a 10-pin connector, which is electrically
connected to the ECM. It is used in the assembly plant to receive information in checking
that the engine is operating properly before it leaves the plant. The code(s) stored in the
ECM’s memory can be read either through a scan tool, (a diagnostic scanner that plugs into
the DLC connector), or by counting the number of flashes of the Malfunction Indicator Lamp
when the diagnostic code tool is installed and SERVICE mode is selected.
73053
DLC Connector
Once the diagnostic code tool has been connected, the ignition switch must be moved to
the ON position, with the engine not running. At this point, the Malfunction Indicator Lamp
should flash Code 12 three times consecutively. This would be the following flash sequence:
flash, pause, flash-flash, long pause, flash, pause, flash-flash, long pause, flash, pause,
flash-flash. Code 12 indicates that the ECM’s diagnostic system is operating. If Code 12 is
not indicated, a problem is present within the diagnostic system itself, and should be ad-
dressed by consulting the appropriate diagnostic chart in “Diagnostics.”
Following the output of Code 12, the Malfunction Indicator Lamp will indicate a diagnostic
code three times if a code is present, or it will simply continue to output Code 12. If more
than one diagnostic code has been stored in the ECM’s memory, the codes will be output
from the lowest to the highest, with each code being displayed three times.
If a scan tool is used to read the codes, follow the manufacturer’s instructions.
SERVICE MODE
When the diagnostic code tool is installed at the Data Link Connector (DLC) and the selector
switch is set at SERVICE, the system will enter what is called the SERVICE mode. In this
mode the ECM will:
1.
2.
3.
Display a Code 12 by flashing the Malfunction Indicator Lamp (indicating the system is
operating correctly).
Display any stored codes by flashing the Malfunction Indicator Lamp. Each code will be
flashed three times, then Code 12 will be flashed again.
Holds ignition advance steady.
NORMAL MODE
Engines can be monitored in the normal mode. Certain parameters can be observed without
changing the engine operating characteristics.
Index
90-861327
OCTOBER 1999
Page 5D-9
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 305 CID, Mercury MerCruiser 350 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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