Chrysler Vehicle User Manual page 254

TJ
REAR WHEEL SPEED SENSOR
DESCRIPTION
A speed sensor is used at each wheel. The front
sensors are mounted to the steering knuckles. The
rear sensors are mounted to the rear brake backing
plate.
OPERATION
The sensors convert wheel speed into a small AC
electrical signal. This signal is transmitted to the
CAB. The CAB convert the AC signal into a digital
signal for each wheel. This voltage is generated by
magnetic induction when a tone wheel passes by the
stationary magnetic of the wheel speed sensor.
A gear type tone ring serves as the trigger mecha-
nism for each sensor. The tone rings are mounted at
the outboard ends of the front and rear axle shafts.
Different sensors are used at the front and rear
wheels (Fig. 1). The front/rear sensors have the same
electrical values but are not interchangeable. The
sensors have a resistance between 900 and 1300
ohms.
REMOVAL
(1) Disconnect sensors at rear harness connectors.
(2) Remove wheel and tire assembly.
(3) Remove brake drum.
(4) Remove clips securing sensor wires to brake
lines, rear axle and, brake hose.
(5) Unseat sensor wire support plate grommet.
(6) Remove bolt attaching sensor to bracket (Fig.
5) and remove sensor.
Fig. 5 Wheel Speed Sensor
1 - TONE WHEEL
2 - WHEEL SPEED SENSOR
INSTALLATION
(1) If original sensor is being installed, remove
any remaining pieces of cardboard spacer from sen-
sor pickup face. Use dry shop towel only to remove
old spacer material.
(2) Insert sensor wire through support plate hole.
Then seat sensor grommet in support plate.
(3) Apply Mopar Lock N' Seal or Loctite
original sensor bolt. Use new bolt if original is worn
or damaged.
(4) Install sensor bolt finger tight only at this time.
(5) If original rear sensor was installed, adjust
sensor air gap to 0.28-1.5 mm (0.011-0.059 in.). Use
feeler gauge to measure air gap (Fig. 6). Tighten sen-
sor bolt to 12-14 N·m (106-124 in. lbs.).
Fig. 6 Setting Air Gap On Original Rear Sensor
1 - WHEEL SPEED SENSOR
2 - BRASS FEELER GAUGE
3 - TONE RING
(6) If new sensor was installed, push cardboard
spacer on sensor face against tone ring (Fig. 7). Then
tighten sensor bolt to 12-14 N·m (106-124 in. lbs.).
Correct air gap will be established as tone ring
rotates and peels spacer off sensor face.
Fig. 7 New Rear Sensor
1 - REAR SENSOR
2 - AIR GAP SPACER ATTACHED TO SENSOR FACE
BRAKES - ABS 5 - 45
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