TROUBLE CODE DIAGNOSTICS - 454/502 MAG MPI & 8.2L MPI
SERVICE MANUAL NUMBER 23
Code 51 (1 of 1): Calibration Memory Failure (Non-Scan)
72801
CIRCUIT DESCRIPTION:
This test allows the ECM to check for a calibration failure by comparing the calibration value
to a known value stored in the EEPROM.
This test is also used as a security measure to prevent improper use of calibrations or
changes to these calibrations that may alter the designed function of the EFI system.
TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic table.
STEP 2: This step checks to see if the fault is present during diagnosis. If present, the ECM
is not functioning correctly and must be replaced.
DIAGNOSTIC AIDS:
An intermittent Code 51 may be caused by a bad cell in the EEPROM that is sensitive to
temperature changes. If Code 51 failed more than once, but is intermittent, replace ECM.
An intermittent problem may be caused by a poor or corroded connection, rubbed through
wire connection, a wire that is broken inside the insulation, or a corroded wire.
Any circuitry that is suspected as causing the intermittent complaint should be thoroughly
checked for backed-out terminals, improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wiring connections, corroded terminals and/or wiring,
or physical damage to the wiring harness. After repairs, clear codes following “Clearing
Codes” at the front of this section. Failure to do so may result in codes not properly being
cleared.
STEP
ACTION
VALUE
YES
NO
PROCEED TO
Go to
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
OBD
System
1
–
Step 2
Check
1.
2.
procedure.
Ignition ON.
Clear trouble code using clearing codes
2
Does code 51 reset?
–
Step 4
Step 3
Faulty is not present at this time. Refer to
“Diagnostic Aids” on facing page.
3
4
–
–
–
–
–
–
Replace ECM and verify code does not reset.
Index
Page 5F-20
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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