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Vehicle Speed Calibration (J1939-Trans)
OEM
Description:
If a value is programmed into the Vehicle Speed
Calibration (J1939 - Trans) parameter the ECM will use
the data that is received from the transmission controller
over the J1939 data link to calculate vehicle speed.
The Vehicle Speed Cal (J1939-Trans) parameter value
represents the Transmission Output Shaft revolutions
per mile. If this parameter is not programmed, the
ECM use one of the other vehicle speed inputs for
calculations.
When the ECM is confi gured to receive Vehicle Speed
information from an Electronic Transmission Control Unit
via the J1939 datalink, the attached transmission must
be capable of supporting the J1939 ETC1 Broadcast
Message that provides the transmission output shaft
speed.
OEM Responsibilities:
• Determine if the transmission is capable of support-
ing the required ETC1 message protocol.
• Determine the parameter value to be programmed
for a given chassis by one of the methods listed
below.
Parameter Calculation Methods:
Method 1
Vehicle Speed Cal (J1939-Trans) =
Transmission Output Shaft revolutions per mile
Method 2
Vehicle Speed Cal (J1939-Trans) =
Transmission Speed Sensor pulse per mile
Number of teeth on the output shaft chopper wheel
Method 3
Vehicle Speed Cal (J1939-Trans) =
Tire revolutions per mile x Axle ratio
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 revs per
mile
(0 rev per km)
65000 revs per
mile
(43000 revs per
km)
Not
Programmed
Vehicle Speed Parameters