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Retrieving Codes
OVERVIEW OF FORD CODE RETRIEVAL PROCESS
Chapter 4 24
3. It records and retains in its memory (not applicable to
MCU systems) a record of faults that occurred in the past
but are no longer present. The vehicle's computer keeps
these Fault Codes in its memory for a specific period of
time (40 Warm Up cycles* for most fault Codes, 80 Warm
up cycles for others) even if the problems that caused
these codes to be set in the first place are no longer
present.
*Warm-up Cycle - A Warm-up Cycle is defined as vehicle
operation (after an engine off period) where the engine
temperature rises at least 40°F (22°C) from the
temperature present when the vehicle was first started,
and the engine temperature reaches at least 160°F (70°C).
NOTE:
The Code Reader does not generate codes. The Code
Reader serves as a “key” that links to, and opens
communication with the vehicle's computer to prompt the
computer to perform Self Tests, and to receive test results or
retrieve codes.
OVERVIEW OF FORD CODE RETRIEVAL PROCESS
Ford’s computer self-diagnostic system is divided into three
main sections: 1. "Key On Engine Off" (KOEO) Self Test, 2.
"Continuous Memory" (CM) Self-Test and 3. "Key On Engine
Running" (KOER) Self Test. These Self-Tests are specially
designed to monitor and/or test the various components and
circuits that are controlled by the vehicle's computer, and to
save and/or transmit diagnostic test results to the Code
Reader in the form of numerical fault codes.
•
The “Continuous Memory” Self Test is designed to run
continuously whenever the vehicle is in normal operation.
If a fault is detected by the “Continuous Memory” Self
Test, a fault code is saved in the vehicle's computer
memory for later retrieval.
NOTE:
Continuous Memory codes only apply to EEC-IV
systems and are retrieved during the KOEO Self Test.
•
Ford designed its On-Board Diagnostic Self Tests in such
a way that in order to properly diagnose a problem, you
must performed all
the Self Tests, in the proper sequence.
As described above, some tests are designed to detect
problems only when the vehicle is in normal operation,
some tests are designed to activate components and detect
problems only with the Key On and Engine Off, and other
4
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