Vehicle Speed Sensor; Vss Location; Vss Removal/Installation; Description - Jeep Wrangler 2001 Service Manual

21s - 74 MANUAL-NV3550

VEHICLE SPEED SENSOR

DESCRIPTION

The 3-wire Vehicle Speed Sensor (VSS) is located
on the speedometer pinion gear adapter. If equipped
with 4WD, this adapter is located on the extension
housing of the transfer case (drivers side). If
equipped with 2WD, this adapter is located on the
left side of the transmission extension housing.
OPERATION
The VSS is a 3-circuit (3–wire), magnetic, hall-ef-
fect sensor.
The 3 circuits are:
• A 5-volt power supply from the Powertrain Con-
trol Module (PCM).
• A ground is provided for the sensor though a
low-noise sensor return circuit in the PCM.
• An input to the PCM is used to determine vehi-
cle 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 sen-
sor, 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.
REMOVAL
The Vehicle Speed Sensor (VSS) is located on the
speedometer pinion gear adapter. If equipped with
4WD, this adapter is located on the transfer case
extension (left side) (Fig. 128). If equipped with 2WD,
this adapter is located on the extension housing of
the transmission (left side).
(1) Raise and support vehicle.
(2) Disconnect electrical connector from sensor by
pushing slide tab (Fig. 128). After slide tab has been
positioned, push in on secondary release lock (Fig.
128) on side of connector and pull connector from
sensor.
(3) Remove sensor mounting bolt (Fig. 129).
(4) Remove sensor (pull straight out) from speed-
ometer pinion gear adapter (Fig. 129). Do not remove
gear adapter from transmission.
2001 JEEP WRANGLER
1 - SENSOR ELECTRICAL CONNECTOR
2 - SLIDE TAB
3 - 4WD TRANSFER CASE EXTENSION
4 - VEHICLE SPEED SENSOR
5 - RELEASE LOCK
1 - ELECTRICAL CONNECTOR
2 - SENSOR MOUNTING BOLT
3 - O-RING
4 - SPEEDOMETER PINION GEAR
5 - SPEEDOMETER PINION GEAR ADAPTER
6 - O-RING
7 - VEHICLE SPEED SENSOR
Fig. 128 VSS Location
Fig. 129 VSS Removal/Installation
TJ