K 2500 Truck 4WD V8-6.5L DSL Turbo VIN S (1998)
Government regulations require that the engine operating conditions are to be captured whenever the MIL is illuminated. The data that is captured is
called Freeze Frame data. The Freeze Frame data is very similar to a single record of operating conditions. Whenever the MIL is illuminated, the
corresponding record of operating conditions is recorded to the Freeze Frame buffer.
Each time a diagnostic test reports a failure, the current engine operating conditions are recorded in the failure records buffer. A subsequent failure
will update the recorded operating conditions. The following operating conditions for the diagnostic test which failed typically include the following
parameters:
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The Air Fuel Ratio
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The Air Flow Rate
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The Fuel Trim
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The Engine Speed
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The Engine Load
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The Engine Coolant Temperature
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The Vehicle Speed
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The TP Angle
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The MAP/BARO
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The Injector Base Pulse Width
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The Loop Status
Freeze Frame data can only be overwritten with the data associated with a misfire or a fuel trim malfunction. The data from these faults take
precedence over data that is associated with any other fault. The freeze frame data will not be erased unless the associated history DTC is cleared.
Data Link Connector (DLC)
The provision for communicating with the control module is a Data Link Connector (DLC). The DLC is usually located under the instrument panel.
The DLC is used in order to connect to a scan tool. Some common uses of the scan tool are listed below:
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Identifying stored Diagnostic Trouble Codes (DTCs)
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Clearing the DTCs
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Performing the output control tests
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Reading the serial data
Control Module Learning Ability & Reprogramming (Flashing)
CONTROL MODULE LEARNING ABILITY
The control module has a learning ability which allows the control module to make corrections for minor variations in the fuel system in order to
improve driveability. Whenever the battery cable is disconnected, the learning process resets.
The driver may note a change in vehicle performance. In order to allow the PCM to re-learn to drive the vehicle at part throttle with moderate
acceleration. The vehicle may also operate at idle conditions until the normal performance returns.
REPROGRAMMING (FLASHING) THE CONTROL MODULE
Some vehicles allow the reprogramming of the control module without removal from the vehicle. This provides a flexible and a cost-effective method
of making changes in software and calibrations.
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Refer to the latest Techline information on reprogramming or flashing procedures.
