MerCruiser 305 CID (5.0L) Service Manual page 631

DIAGNOSTICS
Diagnostic Circuit Check
IMPORTANT: All references to Scan Tool work with either the Quicksilver Digital Diag-
nostic Tool or the Rinda Scan Tool.
The Diagnostic Circuit Check is an organized approach to identifying a problem created by
an electronic engine control system malfunction.
NOTE: A scan tool that displays faulty data should not be used. This could result in misdiag-
nosis and unnecessary parts replacement.
The scan tool data listed in the following table may be used for comparison after finding the
on-board diagnostics functioning properly and no trouble codes displayed. The "Typical
Data Values" are intended to represent what a normally functioning system would display.
Only the parameters listed in the scan position column below are used in this manual. If a
scan reads other parameters, the values are not recommended for use in diagnosing. If all
values are within the range illustrated, refer to "Troubleshooting."
Scan Tool Normal Specifications (Idle/Warm Engine/Closed Throttle/Neutral)
rpm
Desired rpm
Coolant Temp.
Manifold Air Temp.
Throttle Position
Throttle Angle
MAP
Baro
Bat
Spark Advance
Knock Retard
Idle Air Control IAC
Minimum IAC Position
Idle Air Control Follower
Injector Pulse Width
Injector On Time Cranking
Fuel Consumption
Time From Start
Memory Calibration Check
Sum
Oil Press/IO Level
Engine Overtemp
Lanyard Stop Mode
1
: MCM will read I/O Level and MIE will read Trans.
2
: Refer to "Engine and Tune-Up Specifications."
Index
Page 5G-4
Scan Position
rpm
rpm
° F(° C)
° F (° C)
Volts
0-100 %
Volts or kPa
Volts or kPa
Volts
Degrees
Degrees
Counts (Steps)
Counts (Steps)
Counts (Steps)
msec.
msec.
GPH (L/h)
0:00:00-1092:00
Calibration Check Sum
1
OK/LO
OK/Overheating
OFF/ON
Units Displayed
600-700 rpm
600 or 650 rpm (Depends on Model
150-170° F (66-77° C)
Varies with Ambient Temperature
.4 to .8 Volts
0-1%
1-3 Volts or (45-55 kPa) (Depends
on Vacuum and Baro Pressure)
3-5 Volts (Depends on Altitude and
Barometric Pressure)
12.0-14.5 Volts
-10 to 30°
0°
0-40 Counts
0-40 Counts
0 Counts
2-3 msec.
2.5–3.5 msec. (Depends on Water/
Air Temperature)
1-2 GPH(3.7-7.5 L/h)
Varies
Varies with Software revision in ECM
OK
OK
OFF
SERVICE MANUAL NUMBER 24
Typical Data Value
90-861327--1 OCTOBER 1999
2)