2002 JEEP GRAND CHEROKEE 4WD

POSITION SENSOR
DESCRIPTION
The transfer case position sensor (Fig. 95) is an
electronic device whose output can be interpreted to
indicate the transfer case's current operating mode.
The sensor consists of a five position, resistive multi-
plexed circuit which returns a specific resistance
value to the Powertrain Control Module (PCM) for
each transfer case operating mode. The sensor is
located on the top of the transfer case, just left of the
transfer case centerline and rides against the sector
plate roostercomb. The PCM supplies 5VDC (+/-
0.5V) to the sensor and monitors the return voltage
to determine the sector plate, and therefore the
transfer case, position.
OPERATION
During normal vehicle operation, the Powertrain
Control Module (PCM) monitors the transfer case
position sensor return voltage to determine the oper-
ating mode of the transfer case. Refer to the Operat-
ing Mode Versus Resistance table for the correct
resistance for each position (Fig. 96).
OPERATING MODE VERSUS RESISTANCE
SENSOR POSITION OPERATING MODE SENSOR RESISTANCE (ohms)
1 2WD 1124-1243
2 4WD PART TIME 650-719
3 4WD FULL TIME 389-431
4 NEUTRAL 199-221
5 4WD LOW 57-64
Fig. 96 Position Sensor Linear Movement
1 - POSITION 1 - 10mm  0.5mm
2 - POSITION 2 - 12mm  0.5mm
3 - POSITION 3 - 14mm  0.5mm
4 - POSITION 4 - 16mm  0.5mm
5 - POSITION 5 - 18mm  0.5mm
6 - POSITION 6 - 20mm 0.5mm - FULL EXTENSION
Fig. 95 Transfer Case Position Sensor and
Connector
1 - TRANSFER CASE POSITION SENSOR CONNECTOR
2 - TRANSFER CASE POSITION SENSOR
3 - TRANSFER CASE
4 - OUTPUT SPEED SENSOR CONNECTOR
WJTRANSFER CASE - NV242 21 - 311

CONDITION POSSIBLE CAUSE CORRECTION
NOISY INÐOR JUMPS OUT OF
4WD LOW RANGE1. Transfer case not completely
engaged in 4WD LOW (possibly
from shift to 4L while rolling)1. Stop vehicle, shift transfer case
to neutral, then shift back to 4WD
LOW
2. Shift linkage loose, binding, or is
misadjusted2. Tighten, lubricate, or repair
linkage as necessary. Adjust linkage
if necessary
3. Range fork cracked, inserts
worn, or fork is binding on shift rail3. Disassemble unit and repair as
necessary
4. Annulus gear or lockplate worn
or damaged4. Disassemble unit and repair as
necessary
LUBRICANT LEAKING FROM
OUTPUT SHAFT SEALS OR FROM
VENT1. Transfer case over filled 1. Drain to correct level
2. Vent closed or restricted 2. Clear or replace vent if necessary
3. Output shaft seals damaged or
installed correctly3. Replace seals. Be sure seal lip
faces interior of case when installed.
Also be sure yoke seal surfaces are
not scored or nicked. Remove
scores and nicks with fine
sandpaper or replace yoke(s) if
necessary.
REMOVAL
(1) Shift transfer case into NEUTRAL.
(2) Raise vehicle.
(3) Remove transfer case drain plug and drain
transfer case lubricant.
(4) Mark front and rear propeller shaft yokes for
alignment reference.
(5) Support transmission with jack stand.
(6) Remove rear crossmember and skid plate, if
equipped (Fig. 4).
(7) Disconnect front propeller shaft from transfer
case at companion flange. Remove rear propeller
shaft from vehicle. (Refer to 3 - DIFFERENTIAL &
DRIVELINE/PROPELLER SHAFT/PROPELLER
SHAFT - REMOVAL)
CAUTION: Do not allow propshafts to hang at
attached end. Damage to joint can result.
(8) Disconnect transfer case cable from range
lever.
(9) Disconnect transfer case vent hose (Fig. 5).
(10) Support transfer case with transmission jack.
(11) Secure transfer case to jack with chains.
(12) Remove nuts attaching transfer case to trans-
mission.
(13) Pull transfer case and jack rearward to disen-
gage transfer case (Fig. 5).
(14) Remove transfer case from under vehicle.
DISASSEMBLY
Position transfer case on shallow drain pan.
Remove drain plug and drain lubricant remaining in
case.
Fig. 4 Crossmember Removal
1 - CROSSMEMBER
2 - REAR TRANSMISSION MOUNT
WJTRANSFER CASE - NV247 21 - 317
TRANSFER CASE - NV247 (Continued)

(M)Malfunction Indicator Lamp (MIL) illuminated during engine operation if this DTC was recorded
(depending if required by CARB and/or EPA). MIL is displayed as an engine icon on instrument panel.
(G)Generator lamp illuminated
Generic Scan
Tool P-CodeDRB Scan Tool Display Brief Description of DTC
P0712 (M) Trans Temp Sensor Voltage Too Low Voltage less than 1.55 volts (4-speed auto. trans. only).
P0713 Trans Temp Sensor Voltage Too
HighTransmission fluid temperature sensor input above
acceptable voltage. Was MIL code 37.
P0713 (M) Trans Temp Sensor Voltage Too
HighVoltage greater than 3.76 volts (4-speed auto. trans.
only).
P0720 (M) Low Output SPD Sensor RPM,
Above 15 MPHThe relationship between the Output Shaft Speed Sensor
and vehicle speed is not within acceptable limits.
P0720 (M) Low Output Spd Sensor RPM Above
15 mphOutput shaft speed is less than 60 rpm with vehicle speed
above 15 mph (4-speed auto. trans. only).
P0740 (M) Torq Con Clu, No RPM Drop at
LockupRelationship between engine and vehicle speeds
indicated failure of torque convertor clutch lock-up system
(TCC/PTU solenoid)
P0743 (M) Torque Converter Clutch Solenoid/
Trans Relay CircuitsAn open or shorted condition detected in the torque
converter clutch (part throttle unlock) solenoid control
circuit. Shift solenoid C electrical fault - Aisin transmission
P0743 (M) Torque Converter Clutch Solenoid/
Trans Relay CircuitsAn open or shorted condition detected in the torque
converter part throttle unlock solenoid control circuit (3 or
4-speed auto. trans. only).
P0748 (M) Governor Pressur Sol Control/Trans
Relay CircuitsAn open or shorted condition detected in the Governor
Pressure Solenoid circuit or Trans Relay Circuit in JTEC
RE transmissions.
P0748 (M) Governor Pressure Sol Control/Trans
Relay CircuitsAn open or shorted condition detected in the governor
pressure solenoid or relay circuits (4-speed auto. trans.
only).
P0751 (M) O/D Switch Pressed (Lo) More Than
5 MinutesOverdrive override switch input is in a prolonged
depressed state.
P0751 (M) O/D Switch Pressed (LO) More Than
5 MinOverdrive Off switch input too low for more than 5
minutes (4-speed auto. trans. only).
P0753 (M) Trans 3-4 Shift Sol/Trans Relay
CircuitsAn open or shorted condition detected in the overdrive
solenoid control circuit or Trans Relay Circuit in JTEC RE
transmissions. Was MIL code 45.
P0753 (M) Trans 3-4 Shift Sol/Trans Relay
CircuitsAn open or shorted condition detected in the transmission
2-4 shift solenoid circuit (4-speed auto. trans. only).
P0756 AW4 Shift Sol B (2-3) Functional
FailureShift solenoid B (2-3) functional fault - Aisin transmission
P0783 (M) 3-4 Shift Sol, No RPM Drop at
LockupThe overdrive solenoid is unable to engage the gear
change from 3rd gear to the overdrive gear.
P0801 Reverse Gear Lockout Circuit Open
or ShortAn open or shorted condition detected in the transmission
reverse gear lock-out solenoid control circuit.
P0830 Clutch Depressed Switch Circuit Problem detected in clutch switch circuit.
P0833 Clutch Released Switch Circuit Problem detected in clutch switch circuit.
P0836 4WD Mux Switch Circuit
P0837 4WD Mux Switch Performance
25 - 10 EMISSIONS CONTROLWJ
EMISSIONS CONTROL (Continued)