Vehicle Speed Sensor

Fig 13 Vehicle Speed Sensor Location - 2WD - Typical:

Fig 14 Vehicle Speed Sensor Location - 4WD - Typical:

DESCRIPTION
The sensor input is used by the powertrain control module (PCM) to determine vehicle speed and distance traveled.

OPERATION
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 Manifold Absolute Pressure (MAP) value. Under idle conditions, the PCM adjusts the IAC motor to maintain a desired engine speed.

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).

CIRCUIT OPERATION
The Powertrain Control Module (PCM) supplies 5 Volts to the vehicle speed sensor on circuit K7. Circuit K7 connects B31 of the PCM.

Circuit G7 from the vehicle speed sensor provides an input signal to the PCM. The G7 circuit connects to cavity B27 of the PCM.

The PCM provides a ground for the vehicle speed sensor signal (circuit G7) through circuit K4. Circuit K4 connects to cavity A4 of the PCM.