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1990 Jeep Service & Repair Manual
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1 9 9 0
SERVICE
MANUAL

Jeep
ELECTRICAL
SERVICE MANUAL
1990 JEEP VEHICLES
To order the special service tools used and illus-
trated, please refer to the instructions on inside
back cover.
^fe CHRYSLER
W MOTORS
SERVICE & PARTS
OPERATIONS
NO PART OF THIS PUBLICATION MAY BE RE-
PRODUCED, STORED IN A RETRIEVAL SYS-
TEM, OR TRANSMITTED, IN ANY FORM OR
BY ANY MEANS, ELECTRONIC, MECHANI-
CAL, PHOTOCOPYING, RECORDING, OR
OTHERWISE, WITHOUT THE PRIOR WRIT-
TEN PERMISSION OF CHRYSLER MOTORS.
Jeep/Eagle reserves the right to make changes in design or to make additions
to or improvements in its products without imposing any obligations upon itself
to install them on its products previously manufactured.
Litho in U.S.A. Copyright © 1989 Jeep/Eagle Corporation 25M889


FOREWORD
The information contained in this service manual has
been prepared for the professional automotive techni-
cian involved in daily repair operations. Information in
this manual is divided into groups. Each group covers
a general vehicle system (brakes, steering, body, etc.).
Each group is further divided to address individual com-
ponents or systems within the group.
The Component and System Index, located at the back
of this manual, will assist you in locating the correct
group for the component or system you require.
These groups contain general information, diagnosis,
testing, adjustment, removal and installation, disas-
sembly and assembly procedures for the components.
The diagnosis charts are designed to help you locate
and correct problems with a systematic approach. The
tab locator at the right side of this page will help you
quickly locate the first page of each group. The first
page of each group contains an alphabetical index to
assist in the location of the component or system.
The information, description, testing procedures and
specifications were in effect at the time this manual was
released for printing.
Chrysler Motors reserves the right to change testing
procedures, specifications, diagnosis, or repair methods
at any time without prior notice or incurring obligation.
The information describing the operation and use of
standard and optional equipment is included in the
Operating Instructions and Product Information man-
ual located in the glove box.
NOTE: FOR MECHANICAL INFORMATION,
REFER TO THE "ENGINE, CHASSIS & BODY
SERVICE MANUAL
59
- JEEP VEHICLES.
GROUP TITLE
— Introduction
8A Battery
SB Storting System
8C Charging System
8P Ignition
8E Instrument Panel
8F iadio
f
Antenna & Speakers
8G Horns
8H Cruise Control
8J Multi-Function Switch & Hazard
SEC Windshield Wipers & Washers
8L Lamps
8M Seat Belt Warning Systems
8N Rear Window Defogger
8P Power Door Locks
81 Power Seats
8S Power Windows
ST Power Mirrors
8W Wiring Diagrams
J901N-6

INTRODUCTION
pu
70
13
INTRODUCTION
VEHICLE SAFETY CERTIFICATION LABELS
A safety certification label (Fig. 1) is attached to all
vehicles to certify that they conform to Federal motor
vehicle safety certificate standards. The label lists the
month and year of manufacture, gross vehicle weight
rating (GVWR) and gross axle weight rating (GAWR).
The label is located on the door pillar (driver's side).
TIRE INFLATION LABEL
Check the tires for visible signs of wear which may
indicate underinflation or a need for front-end align-
ment, tire rotation or wheel balancing. Also check for
bulging, cracks or other road hazard damage. Check
and adjust the inflation pressures according to the spec-
ifications. The tire pressure specification sticker is lo-
cated on the glove box door (Fig. 2).
JEEP CHEROKEE.
TIRE INFLATION
PRESSURES p.s.i.
inflatetirescoldbeforerunning
DO NOT reduce pressure If tires
are warm.
Sf 8952 000 713 USA
FULL
«*«cyi. 10 AO
pits/rsftis 30 m
piH/KKi m to
»tlf/7SRlf a» s®
GLOVE BOX
DOOR
Fig. 2 Tire Inflation Pressures
J891N-3
VEHICLE IDENTIFICATION NUMBER (WIN)
The Vehicle Identification Number (VIN) is located
on the left side of the instrument panel at the base of the
windshield. All VIN's contain 17 characters in a com-
bination of letters and numbers that provide specific
information about the vehicle (Fig. 3).
J89IN-2
Fig. 1 Safety Certification Labels

INTRODUCTION 3
Country
1= U.S.
2 = Canada
Make
J = Jeep
Vehicle
type
4 = MPV
6 = Incomplete
7 = Truck
GVWR
E = 3001-4000
F = 4001-5000
G = 5001-6000
H = 6001-7000
Line
J = Cherokee - 4WD
T = Cherokee-2WD
N = Wagoneer - 4WD
Y = Wrangler - 4WD
S = Grand Wagoneer -
J = Comanche - 4WD
T = Comanche - 2WD
4WD
7
L
Series
1 = "S" (E)
2 = Base (L)
3 = Pioneer/Islander (M)
4 = Sahara (H)
5 = Laredo/Grand (P)
6 = Eliminator (S)
7 = Limited (X)
Engine
E = 2.5 Litre, 1-4
L = 4.0 Litre, 1-6
T = 4.2 Litre, 1-6
7 = 5.9 Litre, V-8
Sequential
Serial Number
Six Digit Numbers
z
Check Digit
Number or Letter
Body
6 = 2-Dr. Pickup
7 = 2-Dr. Wagon
8 = 4-Dr. Wagon
9 = 2-Dr. Open Body
L 000001
1
Plant Location
J = Brampton
L = Toledo #1
P = Toledo #2
J901N-3
Fig. 3 Vehicle Identification Number (VIN)
BODY CODE PLATE
A metal Body Code Plate is attached to the driver's
side of the dash panel in the engine compartment (Fig.
4). There are up to seven (7) lines of information on this
plate. Information reads from left to right, starting with
line 1 at the bottom of the plate to line 7 at the top.
Refer to the body code plate chart (lines 1 thru 3) for
detailed information.
PRIMARY SECONDARY
PAINT PAINT
VINYL ROOF
CODE
VEHICLE
ORDER-
NUMBER
PAINT-
(3)
PROCEDURE (2)
0)
XXX >XXXXX) X XXX xxxxxx
xxx xxxx XXXX XXXX XXX
VEHICLE
MODEL
•NUMBER
ENGINE
—CODE
TRANSMISSION VEHICLE IDENTIFICATION
CODE NUMBER
MARKET U-C-B-M
CODE
Fig. 4 Body Code Plate
INTERIOR
TRIM CODE
90IN-3
Lines 4 thru 7, of the body code plate, are sequenced
on the plate as follows:
• 3 digit sales codes
• 3 digit numeric codes
• 6 digit SEC codes
Line #1 Digits 1, 2, 3 Transmission Sales Code
Digit 4 Open Space
Digit 5 Market Code-U-C-B-M
Digit 6 Open Space
Digit 7 thru 23 Vehicle Identification
Number
Line #2 Digits 1, 2, 3 Paint Procedure
Digit 4 Open Space
Digits 5, 6, 7, 8 Primary Paint
Digit 9 Open Space
Digits 10, 11, 12, 13 Secondary Paint
Digit 14 Open Space
Digits 15, 16, 17, .18 Trim Code
Digit 19 Open Space
Digits 20, 21, 22 Engine Sales Code
Digit 23 Open Space
Line #3 Digits 1 thru 12 Vehicle Order Number
Digit 13 Open Space
Digits 14, 15, 16 Vinyl Roof Code
(Door Combo Code—
Pillette)
Digit 17 Open Space
Digits 18 thru 23 Model

When there is an SEC code to be punched on the body
code plate and there is not enough room left on a line to
punch the full 6 digits, the balance of that line will be
left blank and the SEC code will be punched on the next
line.
The last nine positions of line #7 will contain a two
digit species, when applicable, and a six digit gateline
sequence number (the last six numbers of the VIN).
The last code shown on either plate will be followed
by END. When two plates are required, the last code
space on the first plate will show CTD (for continued).
When a second plate is required, the first four spaces
of each line will not be used due to overlap of the plates.
ENGINE BUILD DATE CODE
The engine Build Date Code is located:
• 2.5L Engine - On a machined surface on the right side
of the cylinder block between the No. 3 and No. 4 cyl-
inders.
• 4.0L and 4.2L Engines - On a machined surface on the
right side of the cylinder block between the No. 2 and
No. 3 cylinders.
• 5.9L Engine - On a plate attached to the right bank
cylinder head cover.
The digits of the code identify the year (1st), month
(2nd & 3rd), engine type/fuel system/compression ratio
(4th & 5th), and day (6th & 7th) of engine build (Fig. 5).
EXAMPLE: 903MXO3
1st 2nd/3rd 4th/5th 6th/7th
Digit Digit Digit Digit
(Year) (Month) (Type) (Day)
7-1987 01-12 HX 01-31
8-1988 AAX
9-1989 CX
0-1990 NX
Letter CID Fuel Comp.
Code Liter System Ratio
HX 150-2.5L TBI 9.2:1
MX 243-4.0L MPI 8.8:1
CX 258-4.2L 2V 9.2:1
NX 360-5.9L 2V 8.25:1
1990 MODEL IDENTIFICATION CHART
The Model Identification Chart identifies descriptive
codes for all Jeep vehicles (Fig. 6). These codes are used
in captions and references throughout this service man-
ual. These Model codes are not to be confused with the
Vehicle Identification Number (VIN) coding or other
body style references.
VEHICLE NAME MODEL
GRAND WAGONEER - 4DR/4WD SJ
COMANCHE (SHORT BED) - 4WD
COMANCHE (SHORT BED) - 2 WD
MJ
COAAANCHE (LONG BED) - 4 WD
COMANCHE (LONG BED) - 2WD
CHEROKEE - 2DR/4WD
CHEROKEE - 4DR/4WD
CHEROKEE - 2DR/2WD XJ
CHEROKEE - 4DR/2WD
WAGONEER - 4DR/4WD
WRANGLER - 4 WD YJ
J901N-9
Fig. 6 Model Identification Chart
J901N-8
Fig. 5 Engine Identification and Build Date Code

J
INTRODUCTION 5
WHEEL TRACK OVERALL
MODEL NAME MODEL BASE PRONT REAR LENGTH WIDTH HEI6TH
cm/in cm/in cm/in
Grand Wagoneer SJ
276.1 150.9 146.8 473.5 190.0 168.7
4 DR-4 WD 108.7 59.4 57.8 186.4 74.8 66.4
Comanche (Short Bed) MJ 286.8 144.8 144.8 455.2 182.2 164.4
2 DR-4 WD/6" Wheels 112.9 57.0 57.0 179.3 71.7 64.7
(Short Bed) 286.8 147.3 147.3 455.2 182.2 164.4
7" Wheels 112.9 58.0 58.0 179.3 71.7 64.7
Comanche (Short Bed) AAJ 287.3 144.8 144.8 455.2 182.2 162.1
2 DR-2 WD/6" Wheels 113.1 57.0 57.0 179.3 71.7 63.8
(Short Bed) 287.3 147.3 146.3 455.2 182.2 162.1
7" Wheels 113.1 58.0 179.3 71.7 63.8
Comanche (Long Bed) MJ 303.3 144.8 144.8 496.6 182.2 164.4
2 DR-4 WD/6" Wheels 119.4 58.0 58.0 195.5 71.7 64.7
(Long Bed) 303.3 144.8 144.8 496.6 182.2 164.4
7" Wheels 119.4 58.0 58.0 195.5 71.7 64.7
Comanche (Long Bed) MJ 303.8
144.8 144.8 496.6 182.2 162.1
2 DR-2 WD/6" Wheels
119.6
58.0 58.0 195.5 71.7 63.8
(Long Bed) 303.8
144.8 144.8 496.6 182.2 162.1
7" Wheels 119.6
58.0 58.0 195.5 71.7 63.8
Cherokee-6" Wheels XJ 257.6 144.8 144.8
420.0 179.1 161.0
2 DR-2 WD 101.4 58.0 58.0
165.3 70.5 63.4
7" Wheels 257.6 144.8 144.8 420.0 179.1 161.0
101.4 58.0 58.0
165.3 70.5 63.4
Cherokee-6" Wheels XJ 257.6 144.8 144.8 420.0 179.1 161.0
4 DR-2 WD 101.4 57.0 57.0 165.3 70.5 63.4
7" Wheels 257.6 147.3 147.3 420.0 179.1 161.0
101.4 58.0 58.0 165.3 70.5 63.4
Wagoneer XJ 257.6 147.3 147.3 420.0 179.1 161.5
4 DR-4 WD 101.4 58.0 58.0 165.3 70.5 63.6
Cherokee-6" Wheels XJ 257.6 144.8 144.8 420.0 179.1 161.0
2 DR-4 WD 101.4 57.0 57.0 165.3 70.5 63.4
7" Wheels 257.6 147.3 147.3 420.0 179.1 161.0
101.4 58.0 58.0 165.3 70.5 63.4
Cherokee-6" Wheels XJ 257.6 144.8 144.8 420.0 179.1 161.0
4 DR-4 WD 101.4 57.0 57.0 165.3 70.5 63.4
7" Wheels 257.6 147.3 147.3 420.0 179.1 161.0
101.4 58.d 58.0 165.3 70.5 63.4
Wrangler YJ 237.2 147.3 147.3 387.6 167.6 176.5
2 DR-4 WD/Hardtop 93.4 58.0 58.0 152.6 66.0 69.5
J901N-4
1990 EXTERIOR DIMENSIONS

6 INTRODUCTION
1990 INTERIOR DIMENSIONS
MODEL MODEL
HEAD
FRONT REAR
cm/(in)
LEG
FRONT REAR
cm/(in)
SHOULDER
FRONT REAR
cm/(in)
HP
FRONT REAR
cm/(in)
Grand
Wagoneer
SJ 94.2 93.5
37.1 36.8
102.9 94.0
40.5 37.0
148.1 148.1
58.3 58.3
153.7 154.7
60.5 60.9
Comanche
(Short Bed)
MJ 100.1 --
39.4 -
109.2 —
43.0 -
140.5
55.3 -
140.5
55.3 -
Comanche
(Short Bed)
MJ 100.1 -
39.4 ~
109.2 «
43.0 -
140.5 -
55.3 «
140.5 -
55.3 --
Comanche
(Long Bed)
MJ 100.1 -
39.4 -
109.2 -
43.0 -
140.5
55.3 -
140.5 --.
55.3 «
Comanche
(Long Bed)
MJ 100.1 -
39.4 -
109.2 -
43.0
140.5
55.3
140.5 --
55.3 --
Cherokee XJ 97.3 96.5
38.3 38.0
105.7 89.7
41.6 35.3
139.7 140.2
55.0 55.2
140.5 113.0
55.3 44.5
Cherokee XJ 97.3 96.5
38.3 38.0
105.7 89.7
41.6 35.3
139.7 140.2
55.0 55.2
140.5 113.0
55.3 44.5
Wagoneer XJ 97.3 96.5
38.3 38.0
104.4 89.7
41.1 35.3
140.5 140.5
55.3 55.3
140.5 113.0
55.3 44.5
Cherokee XJ 97.3 96.5
38.3 38.0
105.7 89.7
41.6 35.3
139.7 140.2
55.0 55.2
140.5 113.0
55.3 44.5
Cherokee XJ 97.3 96.5
38.3 38.0
105.7 89.7
41.6 35.3
139.7 140.2
55.0 55.2
140.5 113.0
55.3 44.5
Wrangler
(Hardtop)
YJ 102.1 102.9
40.2 40.5
100.1 88.9
39.4 35.0
134.8 143.0
53.1 56.3
134.8 91.4
53.1 36.0
J901N-5

INTRODUCTION
TORQUE REFERENCES
Individual Torque Charts appear at the end of many
Groups. Refer to the Standard Torque Specifications
and Bolt Identification Chart in this Group for torques
not listed in the individual torque charts (Fig. 7).
Note that the torque specifications given in the chart
are based on the use of clean and dry threads. Reduce
the torque by 10%when the threads are lubricated with
engine oil and by 20%if new plated bolts are used.
Various sizes of internal and external hex-lob-
ular. (Torx) head fasteners are used as attaching
hardware on numerous components and assem-
blies in Jeep vehicles. Due to the ever-changing
usage and application of automotive fasteners,
Torx-head fasteners may not be identified as such
throughout this manual.
BOLT TORQUE
BOLT
SIZE
GRADES
N-m ft-lbs
(in-lbs)
GRADE 8
N«m ft-lbs
(in-lbs)
1/4-20 11 (95) 14 (125)
1/4-28 11 (95). 17 (150)
5/16-18 23 (200) 31 (270)
5/16-24 27 20 34 25
3/8-16 41 30 54 40
3/8-24 48 35 61 45
7/16-14 68 50 88 65
7/16-20 75 55 95 70
1/2-13 102 75 136 100
1/2-20 115 85 149 110
9/16-12 142 105 183 135
9/16-18 156 115 203 150
5/8-11 203 150 264 195
5/8-18 217 160 285 210
3/4-16 237 175 305 225
J89IN-9
Fig. 7 Grade 5 and 8 Standard Torque
Specifications
METRIC THREAD AND GRADE IDENTIFICATION
Metric and SAE thread notations differ slightly. The
difference is illustrated in Fig. 8.
INCH METRIC
5/16-18 M8 X 1.25
THREAD
MAJOR
DIAMETER
IN INCHES
NUMBER
OF
THREADS
PER INCH
THREAD
MAJOR
DIAMETER IN
MILLIMETERS
DISTANCE
BETWEEN
THREADS IN
MILLIMETERS
Common metric fastener strength property classes
are 9.8 and 12.9 with the class identification embossed
on the head of each bolt (Fig. 9). Some metric nuts will
be marked with single digit strength identification
numbers on the nut face.
METRIC BOLTS—IDENTIFICATION CLASS NUMBERS
CORRESPOND TO BOLT STRENGTH— INCREASING NUMBERS
REPRESENT INCREASING STRENGTH. J89IN-10
Fig. 9 Metric Bolt Identification
SAE strength classes range from grade 2 to 8 with line
identification embossed on each bolt head. Markings
corresponding to two lines less than the actual grade
(Fig. 10). For Example - Grade 7 bolt will exhibit 5
embossed lines on the bolt head.
SAE CLASSIFICATION
GRADE 5 GRADE 8
MARKINGS FOUND
ON TOP OF BOLT
HEAD INDICATE
GRADE
120° 60°
GRADE 2 GRADE 5 GRADE 8
(SAE) BOLTS—IDENTIFICATION MARKS CORRESPOND
TO BOLT STRENGTH—INCREASING NUMBERS
REPRESENT INCREASING STRENGTH.
J89IN-11
Fig. 10 SAE Bolt Identification
PR606B
Fig. 8 Thread Notation (Metric and SAE)
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Complete service repair manual written for the Jeep 1990.
These manuals are your number one source for repair and service information. They are specifically written for the do-it-yourselfer as well as the experienced mechanic. Each manual provides step-by-step instructions based on the complete disassembly of the machine. It is this level of detail, along with hundreds of photos and illustrations, that guide the reader through each service and repair procedure.
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