90-823225--1 10965E-98 - ELECTRONIC FUEL INJECTION (MULTI-PORT AND THROTTLE BODY)
Code 51: Calibration Memory Failure Non-Scan Diagnostics
(1 of 2)
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 pre-
vent 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 circled number(s) on the
diagnostic chart.
1. This step checks to see if the fault is present dur-
ing diagnosis. If present, the ECM is not function-
ing correctly and must be replaced.
IMPORTANT: At the time of printing, vessels with
Fuel Injection were not being field repro-
grammed to correct this failure. Replacement of
the ECM with a factory reprogrammed ECM is
necessary if Code 51 is current and resets when
clearing codes is completed.
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 in-
termittent, replace ECM.
An intermittent problem may be caused by a poor or
corroded connection, rubbed through wire connec-
tion, a wire that is broken inside the insulation, or a
corroded wire.
Any circuitry that is suspected as causing the inter-
mittent 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 har-
ness. After repairs, clear codes following “Clearing
Codes” in “ECM Self-Diagnostics.” Failure to do so
may result in codes not properly being cleared.
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