Discrete Input Circuit Check (Power Reduction Mode) (Non-Scan)
(1 of 2)
TO SYSTEM
RELAY TERM “87”
TAN/
BLU
TO BUZZER
D
C
B
A
121 TAN
TO IGN
PPUPRL
3 PNK
TO AUDIO
WARNING
SWITCHES
BLU/
TAN
TO TACH
GRY
COOLANT OVERTEMP
(TO BUZZER)
121
TO
WHT
LOW OIL PRESSURE/
LOW I/O FLUID (TO BUZZER)
IGN
COIL
TO LOW OIL PRESSURE,
GEAR LUBE SWITCHES
AND TRANS. TEMPERATURE
(MIE)
931 BRN
J1-6
CIRCUIT DESCRIPTION:
TEST DESCRIPTION:
Several discrete switch inputs are utilized by the fuel
injection system to identify abnormal conditions that
may affect engine operation. A pull-up switch is cur-
rentlyusedinconjunctionwiththeECMtodetectcriti-
cal conditions to engine operation.
NOTE:Refer to Section 4C to test transmission tem-
perature switch.
1.
This step checks if wiring from the engine
switches to the ECM is not shorted to ground.
2.
This step ensures that the discrete switches are
functioning properly by changing state.(I/O oil
level, transmission temperature will not change
state.)
If a switch changes states from its normal at-rest
position, that is normally open to closed, the ECM
sensesachangeinvoltageandrespondsbyentering
power reduction mode. (And activating the audio
warning system.)
DIAGNOSTIC AIDS:
NOTE: Power reduction mode is not used 1997 and
later models.
•
Check engine oil and I/O fluid levels, transmis-
sion fluid, overheat.
This engine protection feature allows the driver full
engine power up to 2800 RPM, but disables four fuel
injectors above 2800 RPM until the engine RPM
drops to 1200 RPM.
•
If above diagnostics are performed and no
change in performance is made, refer to “Trou-
bleshooting.”
An intermittent problem may be caused by a poor or
corroded connection, rubbed through wire connec-
tion, or a wire that is broken inside the insulation.
This feature allows the operator a comfortable ma-
neuvering speed while removing the possibility of
high RPM engine operation until the problem is cor-
rected.
Index
5C-84 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
90-823224--2 796
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1993, 1994, 1995, 1996, 1997 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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Marine readers have rated 1993 1997 Mercury-MerCruiser GM V8 454 CID 7.4L and 502 CID 8.2L Marine Engines Service Manual Number 16 4.5 out of 5.0 based on 4 product reviews. Hugely helpful service manual! Perfect. Thank you!
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