JEEP CHEROKEE 1988 Service Repair Manual

Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988
Pages: 1378, PDF Size: 19.9 MB

Page 1301 of 1378

See VACUUM ACTUATOR & SOLENOID IDLE (RPM) table. Reconnect solenoid
connector and vacuum hose.
CURB IDLE SPEED (RPM) TABLE - 4.2L
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Application Man. Trans. Auto. Trans.
50 State ................ 680 ...................... 600
High Altitude ........... 700 ...................... 650
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VACUUM ACTUATOR & SOLENOID IDLE (RPM) TABLE - 4.2L\
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Application Vacuum Actuator Solenoid Energized
Man. Trans. ............ 1100 ...................... 900
Auto. Trans. ............ 900 ...................... 800
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Fig. 6: Adjusting 4.2L Idle RPM
Courtesy of Chrysler Motors.
NOTE: Idle mixture adjustment is not part of a normal tune-up. DO
NOT adjust mixture unless carburetor has been disassembled

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or vehicle fails emissions testing.
IDLE MIXTURE (TACHOMETER (LEAN DROP) PROCEDURE)
NOTE: On 4.2L engines, ensure idle speed and timing are set prior
to adjusting the idle mixture. If mixture adjustment time
exceeds 3 minutes, run engine at 2000 RPM in Neutral for one
minute, and resume adjustment. On 4.0L engines, idle mixture
adjustment is not possible.
4.2L
1) Remove carburetor and locate roll pins blocking idle
mixture screws. Drill through throttle body on closed end of roll pin
hole. Drive pins out with punch. Reinstall carburetor. Install
tachometer.
2) Operate engine to normal operating temperature, and adjust
curb idle speed. Place automatic transmission selector in Drive
(Neutral for manual transmissions). Turn mixture screws inward until
RPM drops. Turn screws outward until highest RPM is reached.
3) Turn mixture screws inward to obtain the correct decrease
in RPM. See LEAN DROP (RPM) table. Adjust both screws equally. When
mixture is correctly adjusted, replace roll pin to block adjustment
screws.
NOTE: If final RPM differs more than 30 RPM from specified curb
idle speed, reset curb idle, and repeat mixture adjustment.
LEAN DROP (RPM) TABLE
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Application Man. Trans. Auto. Trans.
4.2L .................... 50 ........................ 50
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THROTTLE POSITION SENSOR (TPS)
NOTE: Adjustment of TPS only applies to the 4.0L models. It may be
necessary to remove throttle body from intake manifold, to
access sensor wiring harness.
Checking & Adjusting - 4.0L (Automatic Transmission)
1) Locate the square TPS connector. Note connector terminal
identification stamped on the back of the connector. Turn ignition on.
2) Connect voltmeter through back of wiring harness
connector. Connect negative voltmeter lead to terminal "D" and
positive voltmeter lead to terminal "A" to check input voltage. DO NOT
disconnect TPS connector.
3) Hold throttle plate closed against idle stop and note
voltage. Input voltage should be approximately 5 volts. Disconnect
voltmeter positive lead and connect to terminal "B" to measure output
voltage.
4) With throttle plate closed, measure the output voltage.
The output voltage should be approximately 4.2 volts. If output
voltage is not within specification, loosen TPS retaining screws.
5) Partially tighten one retaining screw. Rotate TPS to
obtain correct output voltage. Tighten retaining screws once correct
voltage is obtained.
Checking & Adjusting - 4.0L (Manual Transmission)
1) Turn ignition on. Connect voltmeter through back of wiring
harness connector. Connect negative voltmeter lead to terminal
"B" and positive voltmeter lead to terminal "A". DO NOT disconnect TPS
connector.

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2) Hold throttle plate in the closed throttle position
against idle stop and note input voltage reading. Input voltage should
be approximately 5.0 volts.
3) Disconnect positive lead from terminal "A" and connect to
terminal "C" to check output voltage. Output voltage should be checked
with throttle plates fully closed.
4) Output voltage should be approximately 0.8 volts. If
output voltage is not within specification, loosen TPS bottom
retaining screw and pivot sensor for a large adjustment or top
retaining screw for a fine adjustment.
5) Adjust sensor to obtain correct output voltage. Tighten
retaining screws. Remove voltmeter.
COLD (FAST) IDLE RPM
4.2L
Disconnect and plug EGR valve vacuum hose. With engine
running at normal operating temperature, place fast idle screw on
second step of fast idle cam and against shoulder of high step. Turn
screw to adjust fast idle speed.
FAST IDLE SPEED (RPM) TABLE
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Application Man. Trans. Auto. Trans.
4.2L ................... 1700 ..................... 1700
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AUTOMATIC CHOKE SETTING
Choke coil cover is riveted in place and no adjustment is
necessary or possible.
SERVICING
EMISSION CONTROL
See EMISSIONS section.
SPECIFICATIONS
IGNITION
Distributor
All vehicles use a Motorcraft breakerless solid state
distributor.
PICK-UP COIL RESISTANCE TABLE - OHMS @ 75
F (24C)\
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Application Specification
All Models ....................................... 400-800
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TOTAL SPARK ADVANCE TABLE @ 2000 RPM\
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Application W/ Vac. Advance W/O Vac. Advance
4.0L ................ N/A .......................... N/A
4.2L ............... 30.5
................... 7.5-12.5

Page 1304 of 1378

(1) - Information not available from manufacturer.\
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IGNITION COIL
IGNITION COIL OUTPUT TABLE @ 1000 RPM\
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Application Output
All Models .................................. 24KV Minimum
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IGNITION COIL RESISTANCE TABLE\
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Temperature Primary Ohms Secondary Ohms
75
F (24C) .......... 1.13-1.23 ............. 7700-9300
200F (93C) ............ 1.5 ................... 12,000\
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FUEL SYSTEM
CARBURETORS & FUEL INJECTION TABLE\
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Application Model
4.0L ................................................ MPFI
4.2L ................................... Carter BBD 2-Bbl.
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BATTERY
BATTERY SPECIFICATIONS TABLE\
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Application Cold Cranking Reserve Capacity
** ( 1) Amps Minutes
Standard ................ 421 ....................... 75
Optional ................ 452 ....................... 81
( 1) - At 0
F (-18C).\
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STARTER
All models equipped with Mitsubishi starters.
STARTER SPECIFICATIONS TABLE
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Application Volts Amps Test RPM
All Models ...... 11.22 .......... 80 ........... 2500
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ALTERNATOR
All models use Delco-Remy solid state alternators with
internal voltage regulator.
ALTERNATOR SPECIFICATIONS TABLE
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Application Field Current Rated

Page 1305 of 1378

** Draw @ 12 Volts Amp Output
Standard ......... (1) 4.0-5.0 Amps ................. 56
Optional ......... ( 1) 4.0-5.0 Amps ................. 66
Optional ......... ( 1) 4.0-5.0 Amps ................. 78
( 1) - At 80
F (27C).\
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ALTERNATOR REGULATORS
All models use Delco-Remy solid state regulators, integral
with alternator. Regulator is nonadjustable.
BELT ADJUSTMENT
BELT ADJUSTMENT TABLE TENSION IN LBS. (KG) USING STRAND TENSION GAUGE\
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Application New Belts Used Belts
"V"-Belts ......... 125-155 (57-70) ............... 90-115 (41-52\
)
Serpentine ........ 180-200 (82-91) .............. 140-160 (63-72\
)
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REPLACEMENT INTERVALS
REPLACEMENT INTERVALS TABLE\
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Component Interval (Miles)
Air Filter ........................................ 30,000
Fuel Filter ....................................... 30,000
Oil & Filter ........................................ 7500
PCV Valve ......................................... 30,000
Spark Plugs ....................................... 30,000
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CAPACITIES
FLUID CAPACITIES TABLE\
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Application Quantity
Auto. Trans. (Dexron II)
Wrangler ............................... 8.0 qts. (7.6L)
All Others ............................. 8.5 qts. (8.0L)
Cooling System
Wrangler .............................. 10.5 qts. (9.9L)
All Others ........................... 12.0 qts. (11.4L)
Crankcase (Includes Filter)
Wrangler ............................... 5.0 qts. (4.7L)
All Others ............................. 6.0 qts. (5.7L)
Drive Axle
Front .................................. 2.5 pts. (1.2L)
Rear
Comanche
Standard Capacity .................. 2.5 pts. (1.2L)
Metric Ton Axle .................... 4.8 pts. (2.3L)
All Others ........................... 2.5 pts. (1.2L)
Fuel Tank
Cherokee & Wagoneer
Standard ............................ 13.5 gals. (51L)

Page 1306 of 1378

Optional .............................. 20 gals. (76L)
Comanche
Standard .............................. 16 gals. (60L)
Optional ............................ 23.5 gals. (89L)
Wrangler
Standard .............................. 15 gals. (57L)
Optional .............................. 20 gals. (75L)
Manual Transmission
AX4 .................................... 7.8 pts. (3.7L)
AX5 .................................... 7.4 pts. (3.5L)
BA 10/5 ................................ 3.5 pts. (1.6L)
Transfer Case (Dexron II)
Wrangler .............................. 3.25 pts. (1.5L)
All Others
Command Trac ......................... 2.2 pts. (1.0L)
Select Trac .......................... 3.0 pts. (1.4L)
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SYSTEM REFRIGERANT CAPACITIES TABLE\
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Application Ozs.
All Models ............................................ 36
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Page 1307 of 1378

TU RN S IG NALS & H AZA R D F LA SH ER S

1988 J e ep C hero ke e
1988 Turn Signal & Hazard Light Systems
JEEP
DESCRIPTION
Turn signals and hazard flashers systems use a common turn
signal/hazard light switch assembly mounted within upper steering
column housing.
FLASHER LOCATIONS
Hazard
Mounted on fuse block.
Turn Signal
Mounted on fuse block.
TROUBLE SHOOTING
NOTE: Following trouble shooting is only information available
from manufacturer.
Hazard Lights (Comanche, Cherokee & Wagoneer)
If lights do not come on with hazard switch turned on, check
hazard/stop light fuse by operating stop lights. If fuse is okay,
check turn signal flasher, turn signal/hazard switch, and related
wiring. If only one hazard light does not work, check bulb.
Turn Signals (Comanche, Cherokee & Wagoneer)
If all turn signals do not work, check turn/back-up light
fuse by operating back-up lights. If fuse is okay, check turn signal
flasher, turn signal/hazard switch, and related wiring. If only one
turn signal does not work, check bulb.
TESTING
NOTE: Following trouble shooting is only information available
from manufacturer.
Hazard Indicators (Wrangler)
1) Turn ignition and hazard warning switch "ON". Check for
pulsating voltage at Light Blue (left indicator) and Dark Blue (right\
indicator) wires. If voltage is present, go to next step. If voltage
is not present, replace turn signal switch.
2) Remove bulbs for turn signal indicators. Measure
resistance across bulb terminals. If resistance is zero ohms, replace
light bulb(s). If resistance readings are not zero ohms, go to next
step.
3) Check for pulsating voltage at battery side of bulb
sockets. If voltage is present, go to next step. If voltage is not
present, repair open circuit between socket and turn signal switch
steering column connector.
4) Turn ignition off and check resistance on ground side of
bulb sockets. If resistance is zero ohms, hazard indicator circuit is
okay. If resistance reading is not zero ohms, repair open in ground
circuit.
Hazard Lights (Wrangler)

Page 1308 of 1378

1) Check operation of stop lights. If stop lights come on, go
to next step. If not, check hazard/stop light fuse. If fuse is okay,
check for voltage on battery side of hazard/stop light fuse. If
voltage is not present, repair open circuit between fusible link and
fuse block.
2) Remove hazard flasher and check for voltage on battery
side of hazard flasher at fuse block. If voltage is present, go to
next step. If voltage is not present, repair open circuit to fuse
block.
3) Measure resistance across turn signal flasher terminals.
If resistance across flasher is zero ohms, replace flasher. If
resistance is other than zero ohms, install flasher and turn ignition
on.
4) Check for voltage at Brown wire of turn signal switch
steering column connector. If voltage is present, go to next step. If
voltage is not present, repair open circuit between flasher and turn
signal switch connector.
5) Turn hazard warning switch "ON". Check for pulsating
voltage at Light Blue, Dark Blue, Yellow, and Dark Green wires. If
voltage is present, hazard light circuit is okay. If voltage is not
present, replace turn signal switch.
Turn Signals (Wrangler)
1) Turn ignition on and check operation of back-up lights. If
lights come on, go to step 3). If back-up lights do not come on, check
turn signal/back-up light fuse.
2) If fuse is okay, check for voltage at battery side of turn
signal/back-up light fuse. If voltage is not present, repair open
circuit between fuse block and ignition switch. If voltage is present,
go to next step.
3) Remove turn signal flasher and measure resistance across
flasher terminals. If resistance across flasher is zero ohms, replace
turn signal flasher. If flasher is okay, install flasher and turn
ignition on.
4) Check for voltage on battery side of flasher at fuse
block. If voltage is present, go to next step. If voltage is not
present, repair open circuit to fuse block.
5) Disconnect turn signal switch at steering column
connector. Place turn signal switch in left turn position and measure
resistance between Yellow and Purple wires. If resistance across wires
is zero ohms, replace turn signal switch. If resistance is other than
zero ohms, go to next step.
6) Place turn signal switch in right turn position and
measure resistance between Dark Green and Purple wires. If resistance
across wires is zero ohms, replace turn signal switch. If resistance
is other than zero ohms, turn signal circuit is okay.
Turn Signal Indicators (Wrangler)
1) Turn ignition on. Place turn signal switch in left turn
position and check for pulsating voltage at Light Blue wire. If
voltage is present, go to next step. If voltage is not present,
replace turn signal switch.
2) Place turn signal switch in right turn position and check
for pulsating voltage at Dark Blue wire. If voltage is not present,
replace turn signal switch. If voltage is present, go to next step.
3) Remove bulbs from turn signal indicators. Measure
resistance across bulb terminals. If resistance is zero ohms, replace
light bulb(s). If resistance readings are not zero ohms, turn ignition\
on.
4) Place turn signal switch in left and right turn position
and check for pulsating voltage at battery side of bulb sockets. If
voltage is present, go to next step. If voltage is not present, repair
open circuit between socket(s) and steering column connector.

Page 1309 of 1378

5) Turn ignition off and check resistance on ground side of
bulb sockets. If resistance is zero ohms, turn signal indicator
circuit is okay. If resistance reading is not zero ohms, repair open
in ground circuit.

Page 1310 of 1378

UNIV ER SA L J O IN TS

1988 J e ep C hero ke e
1988 Drive Shafts - Universal Joints
All Manufacturers
MAINTENANCE
Whenever drive shaft is removed from vehicle of if slip yoke
sticks in extension housing seal, clean yoke with solvent. Lubricate
inside diameter of seal with synthetic oil seal lubricant, and outside
diameter of seal with transmission fluid.
OVERHAUL
NOTE: Universal joints should not be disassembled unless external
leakage or damage has occurred.
Before disassembly, scribe alignment marks on yoke and shaft
to allow reassembly in original position. If joints are rusted or
corroded, apply penetrating oil before pressing out bearing cups or
trunnion pin.
CROSS SHAFT & ROLLER TYPE UNIVERSAL JOINTS
There are 2 different retaining methods used for bearing
cups, either snap rings or nylon retainers. Joints with snap rings may
be taken apart and reassembled, using same cross shaft and bearings.
Joints with nylon retainers are disassembled by breaking nylon
retainers. Retainers must be replaced after service.
Removal & Disassembly
1) Disconnect yoke or flange attaching bolts and remove drive
shaft from vehicle.
NOTE: DO NOT use a pry bar to hold drive shaft while loosening
bolts. Damage to bearing seals may result.
Fig. 1: Exploded View of Jeep Constant Velocity Type Universal Joint
2) Remove retaining strap (if equipped). Remove bushing
retainers from yoke. Press out rollers and bearings. Remove last
roller and bushing assembly by pressing on end of cross shaft.

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