Vss (Vehicle Speed Sensor) - Navistar International DT 466 Diagnostic/Troubleshooting Manual

544 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS

VSS (Vehicle Speed Sensor)

Figure 507 Function diagram for the VSS
The function diagram for the VSS includes the
following:
• VSS
• Electronic Control Module (ECM)
• World Transmission Electronic Control (WTEC)
ECM
• Cruise Control
• Power Takeoff
• Road Speed Limit
Function
The VSS is on the left side of the transmission. The
VSS reads the rotation of a 16 toothed gear and
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
produces a sine wave signal. The ECM processes
the sine wave signal to calculate vehicle speed. The
Drivetrain Datalink (CAN 1) transmits the calculated
speed to the speedometer. The calculated speed
also assists in control strategies that include Cruise
Control, Power Takeoff, and Road Speed Limiting.
Allison WTEC MD, HD, and 2000 series transmissions
use an internal VSS that sends a signal to the
transmission module.
processes the signal and sends a square wave signal
to the engine ECM.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
The transmission module