Neon L4-2.0L SOHC (1995)
Vehicle Speed Sensor: Description and Operation
Vehicle Speed Sensor-PCM Input
Fig. 17 Vehicle Speed Sensor -- Automatic Transmission
Fig. 18 Vehicle Speed Sensor -- Manual Transmission
PURPOSE
The sensor input is used by the PCM to determine vehicle speed and distance traveled.
OPERATION
The vehicle 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. Under deceleration conditions, the PCM adjusts the Idle Air Control (IAC)
motor to maintain a desired MAP value.
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 idle
conditions, the PCM adjusts the IAC motor to maintain a desired engine speed.
The vehicle speed sensor signal is also used to operate:
-
Speedometer
-
Speed control
-
Daytime Running Lights (Canadian Vehicles only).