Mercury MerCruiser MCM 454 Mag MPI Service Manual page 782

SERVICE MANUAL NUMBER 23
Code 52 (1 of 2): EEPROM Failure (Non-Scan)
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.
DIAGNOSTIC AIDS:
If DTC 52 failed more than once, but is intermittent, replace the ECM.
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 properly and must be replaced.
Index
90-861326--1 MARCH 1999
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STEP
Was the "On-Board Diagnostic" (OBD) System
1
Check Performed?
2 1. Install Marine Diagnostic Code Tool.
2. Using clear trouble code procedure, clear
trouble code 52.
3. Ignition "ON".
4. Switch Marine Diagnostic Code Tool to
the "Service Mode".
Does trouble code 52 reset?
Replace faulty ECM and verify trouble code
3
does not reset. Is action complete?
ACTION
TROUBLE CODE DIAGNOSTICS - 7.4L MPI
72801
VALUE YES
PROCEED TO
– Step 2
– Step 3
Verify
–
Repair
Page 5G-37
NO
Go to
OBD
System
Check
Refer to
Diag- Diag
nostic nostic
Aids
–