Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Vehicle Speed Sensor: Description and Operation
Vehicle Speed Sensor Operation
Fig. 8 Vehicle Speed Sensor Location-Typical
VEHICLE SPEED AND DISTANCE SENSOR-PCM INPUT
The vehicle speed sensor is located on the speedometer pinion gear adapter (Fig. 8). The pinion gear adapter is located on the extension housing of
the transfer case (drivers side). 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.
