Mercury 305 CID, Руководство по обслуживанию

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90-823225--1 1096 5E-6 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
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. Display a Code 12 by flashing the Malfunction In-
dicator Lamp (indicating the system is operating
correctly).
2. Display any stored codes by flashing the Mal-
function Indicator Lamp. Each code will be
flashed three times, then Code 12 will be flashed
again.
3. The IAC valve moves to its fully extended posi-
tion, blocking the idle air passage. This is impor-
tant to remember, as an attempt to run the vessel
while in SERVICE mode will most likely result in
an abnormally low idle speed or a stalled engine.
4. Holds ignition advance steady.
NORMAL MODE
Engines can be monitored in the normal mode. Cer-
tain parameters can be observed without changing
the engine operating characteristics.
Scan Tools
The ECM can communicate a variety of information
through the DLC connector. This data is transmitted
at a high frequency which requires a scan tool for in-
terpretation.
With an understanding of the data which the tool dis-
plays, and knowledge of the circuits involved, the tool
can be very useful in obtaining information which
would be more difficult or impossible to obtain with
other equipment.
Scan tools do not make the use of diagnostic charts
unnecessary, nor can they indicate exactly where a
problem is in a particular circuit. Tree charts incorpo-
rate diagnosis procedures using a scan tool where
possible or a Diagnostic Code Tool (non-scan) if a
scan tool is unavailable.
EFI Diagnostic Circuit Check
After the visual/physical inspection, the EFI Diagnos-
tic Circuit Check is the starting point for all diagnostic
procedures. Refer to EFI Diagnostic Circuit Check.
The correct procedure to diagnose a problem is to fol-
low two basic steps.
1. Are the on-board diagnostics working? This is
determined by performing the EFI Diagnostic Cir-
cuit Check. Since this is the starting point for the
diagnostic procedures, always begin here. If the
on-board diagnostics are not working, the EFI
Diagnostic Circuit Check will lead to a diagnostic
chart in “Diagnostics” to correct the problem. If
the on-board diagnostics are working correctly,
go to step 2.
2. If there is a code stored: If a code is stored, go di-
rectly to the numbered code chart in “Diagnos-
tics.” This will determine if the fault is still present.
Scan Tool Use with Intermittents
The scan tool allows manipulation of wiring har-
nesses or components with the engine not running,
while observing the scan tool readout.
The scan tool can be plugged in and observed while
running the vessel under the condition when the Mal-
function Indicator Lamp turns ON momentarily or
when the engine driveability is momentarily poor. If
the problem seems to be related to certain parame-
ters that can be checked on the scan tool, they should
be checked while running the vessel. If there does
not seem to be any correlation between the problem
and any specific circuit, the scan tool can be checked
on each position, watching for a period of time to see
if there is any change in the readings that indicates
intermittent operation.
The scan tool is also an easy way to compare the op-
erating parameters of a poorly operating engine with
those of a known good one. For example, a sensor
may shift in value but not set a trouble code. Compar-
ing the senor’s readings with those of the typical scan
tool data readings may uncover the problem.
The scan tool has the ability to save time in diagnosis
and prevent the replacement of good parts. The key
to using the scan tool successfully for diagnosis lies
in the technician’s ability to understand the system he
is trying to diagnose as well as an understanding of
the scan tool operation and limitations. The techni-
cian should read the tool manufacturer’s operating
manual to become familiar with the tool’s operation.