TROUBLE CODE DIAGNOSTICS - 7.4L MPI
SERVICE MANUAL NUMBER 23
Page 5G-68
90-861326--1 MARCH 1999
Code 51 (1 of 1): Calibration Memory Failure (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 EFI.
DIAGNOSTIC AIDS:
If DTC 51 failed more than once, but is intermittent, replace the ECM.
TEST DESCRIPTION:
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.
STEP
ACTION
VALUE
YES
NO
PROCEED TO
1
Was the “On-Board Diagnostic” (OBD) System
Check Performed?
–
Step 2
Go to
OBD
System
Check
2
1. Clear trouble code 51.
Refer to
Diag
2. Ignition “ON”.
Diag-
nostic
Is trouble code reset?
–
Step 3
nostic
Aids
3
Replace faulty ECM and verify trouble code 51
does not reset.
–
Verify
Repair
–
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