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Appendix B: Data Parameter List & Definitions
All data parameters or parameter identification data (PID) listed in Appendix B were
verified on actual vehicles to guarantee their accuracy. Definitions used to describe all
PIDs were obtained from reliable sources and are accurate at the time of printing. It is
possible that some newer vehicles may contain data different from that listed in
Appendix B. Always refer to a vehicle service manual for vehicle-specific PIDs.
Data Parameter List Format
The data parameter list is organized in alphabetical order the same way as on the
OBD II System Tester. For all data parameters, Appendix B will define the data
parameter, tell what type of reading it is (i.e. input, output, or calculated) and give
some helpful tips on what to do if the reading is unsatisfactory. Remember to always
refer to a vehicle service manual for detailed diagnostic procedures for troubleshoot-
ing incorrect data parameter readings.
Types of Data Parameters
INPUT: These data parameters are obtained from sensor circuit outputs.
Sensor circuit outputs are inputs to the vehicles PCM. For example, if
the Oxygen Sensor circuit was generating a 400mV signal, then the
OBD II System Tester would display O2S (v) 0.40.
OUTPUT: These data parameters are
outputs or commands that come directly
from the PCM. For example; the ignition spark advance is controlled
by PCM, on most vehicles, monitoring this PID shows the spark output
from the PCM. The OBD II System Tester would display IGN ADV(°) 10.
CALCULATED: These data parameters are
calculated after analyzing various inputs
VALUE inputs to the vehicles PCM. For example, the engine load. The PCM
calculates this from sensor inputs and displays it in a percentage.
PCM VALUE: Is information that is stored in the PCMs memory and determined to
be useful to the service technician. An example of this is the TROUBLE
CODE value, the DTC that caused a freeze frame capture.
NOTE: Several different causes can have the same parameter indication. For
information on diagnostics consult the vehicle service manuals .
DATA PARAMETER LIST
ABSLT TPS (%) (Absolute Throttle Position Sensor - PCM input)
Display: 0 - 100%
This PID represents how far the throttle plate has been opened by the driver. The TPS
produces a voltage signal proportional to the throttle position. This voltage is converted to
a percentage by the PCM. A low voltage reading calculates to 0%, closed throttle while a
high voltage which equates to 100% reading indicates fully opened throttle.
CALC LOAD (%) (Calculated Engine Load - PCM calculated value)
Display: 0 - 100%
The percentage reading of this PID indicates the amount of load on the engine. The
higher the reading the greater the load on the engine.
The PCM uses engine load to help determine correct air/fuel ratios, spark advance,
idle speed, and emission device operation. Higher engine load conditions will cause the
PCM to increase the injector pulse widths.