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Vehicle Speed Calibration (J1939-ABS)
OEM
Description:
If a value is programmed into the Vehicle Speed
Calibration (J1939 - ABS) paramter the ECM will use the
data that is received from the ABS controller over the
J1939 data link to calculate vehicle speed. The Vehicle
Speed Cal (J1939-ABS) parameter value represents
the ratio of actual tire revolutions per mile divided by
assumed ABS tire revolutions per mile, and is used
with the wheel speed signal (received over the J1939
datalink) to calculate vehicle speed.
It is important to note that if this calibration method is to
be used, the ABS must be able to support the J1939 High
Resolution Wheel Speed Broadcast Message, which
provides wheel speed from the two rear wheels. In
addition to the wheel speed, the ABS will also transmit
the actual revolutions per mile, which should be divided
by the assumed ABS tire revolutions per mile to obtain
the Vehicle Speed Cal (J1939-ABS) parameter.
OEM Responsibilities:
• Determine if the ABS can support the required mes-
sage protocol mentioned above.
• It is recommended that the OEM program the Ve-
hicle Speed Calibration parameter.
Parameter Calculation Method:
Vehicle Speed Cal =
Actual Tire Revolutions Per Mile
Assumed ABS Tire Revolutions Per Mile
Available:
All electronically controlled on-highway engines
covered in this handbook
Range:
Engine
Range
Cat
Default
Minimum Maximum
3126E, C7, C9,
C-10, C-12,
C-15, C-16,
C11, C13, C15
0 6.550
Not
Programmed
Vehicle Speed Parameters