GENERAL SYSTEM DIAGNOSTICS
SERVICE MANUAL NUMBER 23
Discrete Input Circuit Check - Non-Scan - 454 / 502 Mag MPI and 8.2L MPI Only
(1 of 5)
a
b
c
TAN/
D
121 TAN
3 PNK
BLU
PUR
BLU/
TAN
GRY
e
C
B
d
A
g
h
121
WHT
f
931
BRN
i
J1-6
a - To Buzzer
b - To Ignition
c - To Audio Warning Switches
d - To Tach
e - To System Relay Term “87”
f - To Ignition Coil
g - Coolant Overtemp (To Buzzer)
h - Low Oil Pressure/ Low I/O Fluid (To Buzzer) (Trans. Temp. MIE)
i - To Low Oil Pressure And Gear Lube Switches (Trans. Temp. MIE)
CIRCUIT 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 currently used in conjunction
with the ECM to detect critical conditions to engine operation.
If a discrete switch changes states from its normal at-rest position, that is normally open to
closed (or closed to open), the ECM senses a change in voltage and responds by activating
the audio warning system.
TEST DESCRIPTION:
A problem with the discrete circuit system will have to be broken down into several sub-
steps. These will include the following:
•
•
•
Testing the audio warning buzzer.
Testing the individual switches.
Testing the wiring.
Be sure that all items above have been performed prior to replacement of the ECM.
DIAGNOSTIC AIDS:
•
Check engine oil and gear lube levels. Check transmission fluid for overheat condition.
An intermittent problem may be caused by a poor or corroded connection, rubbed through
wire connection, or a wire that is broken inside the insulation.
Index
Page 5E-92
90-861326--1 MARCH 1999
| Categories | Mercury MerCruiser Manuals |
|---|---|
| Tags | Mercury MerCruiser 454 CID, Mercury MerCruiser 502 CID |
| Model Year | 1998, 1999, 2000, 2001 |
| Download File |
|
| Document File Type | |
| Copyright | Attribution Non-commercial |
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Marine readers have rated Mercury MerCruiser GM V8 GM V8 454 CID 7.4L and 502 cid 8.2L Marine Engines Service Manual Number 23 5.0 out of 5.0 based on 1 product reviews. Just need the manual. Wrote review. Can't technically review what I haven't seen yet...