SERVICE MANUAL NUMBER 23
GENERAL SYSTEM DIAGNOSTICS
Discrete Input Circuit Check - Non-Scan 7.4L MPI Only (2 of 5)
NOTE: The ECM should only be replaced after all switches and circuits have been tested
and found to be functioning properly.
TESTING BUZZER
STEP
ACTION
VALUE
YES
NO
PROCEED TO
1
2
1. Key “ON”, Engine “OFF”.
Does buzzer sound?
1. Start engine.
Step 2
Step 6
Step 3
Step 4
Does buzzer sound?
1.
Disconnect TAN/BLU wire at buzzer.
2. Key “ON”, Engine “OFF”.
Touch TAN/BLU wire to ground (–).
3
3.
Does buzzer sound?
Step 4
–
Step 5
–
Buzzer is working properly. Proceed to “Testing
Switches” or “Testing Circuits”.
4
5
Check to ensure that there is battery power (+)
to the PUR wire going to buzzer. If there is,
replace buzzer and verify repair
–
–
–
–
(Starting at Step 1).
Discrete switches may all be functioning prop-
erly.
Proceed to check all discrete circuits to verify
each works properly.
6
TESTING OIL PRESSURE SWITCH
STEP
ACTION
VALUE
YES
NO
PROCEED TO
1.
Disconnect PUR wire from oil pressure
switch.
1
2
2. Engine “OFF”.
Check for continuity between terminal on
3.
switch and ground (–).
Is there continuity?
0 Ohms Step 2
Step 3
1.
Start engine.
2. Check for continuity between terminal on
switch and ground (–).
Is there continuity?
0 Ohms Step 3
Step 4
3
4
Replace oil pressure switch. Verify repair.
Oil pressure switch is working properly.
–
–
–
–
Index
90-861326--1
MARCH 1999
Page 5E-99
| 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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