Vehicle Speed and Distance Sensor
VEHICLE SPEED AND DISTANCE SENSOR-PCM INPUTFig. 11 VSS Location - 2WD:
Fig. 12 VSS Location - 4WD:
The vehicle speed sensor is located on the speedometer pinion gear adapter. The pinion gear adapter is located on the extension housing of the transmission (drivers side-2WD), or on the transfer case (4WD). The sensor input is used by the powertrain control module (PCM) to determine vehicle speed and distance traveled.
The speed sensor generates 8 pulses per sensor revolution. These signals, in conjunction with a closed throttle signal from the throttle position sensor, indicate a closed throttle deceleration to the PCM. When the vehicle is stopped at idle, a closed throttle signal is received by the PCM (but a speed sensor signal is not received).
Under deceleration conditions, the PCM adjusts the Idle Air Control (IAC) motor to maintain a desired MAP value. Under idle conditions, the PCM adjusts the IAC motor to maintain a desired engine speed.