Vehicle Speed Sensor Operation

Fig. 24 Vehicle Speed Sensor--Manual Transmission:

VEHICLE SPEED SENSOR - PCM INPUT (MANUAL TRANSMISSION)
The vehicle speed sensor is located in the transmission extension housing Fig. 24. The sensor input is used by the PCM to determine vehicle speed and distance traveled, manual transmission only. Refer to Transmission Control Module for automatic transmission.

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 the following functions or systems:
- Speedometer
- Speed Control
- Daytime Running Lights (Canadian Vehicles Only)
- Open Throttle IAC position.