Segment:
Compact SUV / Off-Road Vehicle
Key Selling Points:
Off-road capability, iconic design, open-air experience
Direct Competitors 2003:
Toyota 4Runner, Nissan Xterra, Ford Explorer (though Explorer was larger), Suzuki Vitara
Design:
Body-on-frame construction, solid axles (front and rear), removable doors and top
Value Proposition:
Enables DIY repairs, saving significant labor costs compared to professional workshops.
Target Audience:
Jeep Wrangler owners with basic to intermediate mechanical aptitude, DIY enthusiasts, off-roaders.
Primary Coverage:
Full Service and Repair
Secondary Coverage:
Troubleshooting, Diagnostics, Electrical Schematics, Specifications
Type:
Factory Service Manual / Workshop Manual
Format:
Digital (likely PDF, searchable)
Engine:
Engine Overhaul and Rebuilding, Engine Performance, Timing Belt Service Procedures, Firing Orders
Transmission:
Transmission Removal and Installation, Transmission In-Car Servicing
Chassis:
Front End and Alignment, Suspension, U-Joint and CV-Joint Service Procedures
Brakes:
Brake Servicing Procedures, Complete Torque Specifications (relevant to brakes)
Electrical:
Complete Wiring Diagrams, Vacuum Diagrams
Climate Control:
Air Conditioning Service and Capacities
Diagnostic Procedures:
Troubleshooting and Diagnostics, Computer Diagnostic Trouble Tree Charts
Repair Procedures:
Step-by-step repair explanations for all major vehicle systems
Maintenance Procedures:
Routine maintenance tasks, fluid changes, component replacement
Depth:
Comprehensive (from basic maintenance to major component overhaul and rebuilding)
Illustrations Diagrams:
Detailed illustrations, diagrams, depth illustrations
Engine Code And Type:
4.0L Inline-6 (OHV) - AMC/Chrysler 242
Displacement:
3957 cc (242 cubic inches)
Horsepower:
Approx. 190 hp @ 4600 RPM
Torque:
Approx. 235 lb-ft @ 3200 RPM
Fuel Delivery:
Multi-Point Fuel Injection (MPI)
Recommended Fuel:
87 Octane Unleaded Gasoline
Engine Block Material:
Cast Iron
Cylinder Head Material:
Cast Iron
Timing Mechanism:
Timing Chain (no belt to replace on the 4.0L)
Firing Order:
1-5-3-6-2-4
Common Engine Issues 2003:
Cracked cylinder heads (less common in later 4.0L versions), intake manifold gasket leaks, CPS (Crankshaft Position Sensor) failure.
Transmission Type:
NV3550 5-speed Manual Transmission
Transmission Type:
42RLE 4-speed Automatic Transmission
Transfer Case:
NV241OR 2-speed Off-Road Transfer Case (Rock-Trac on Rubicon models, NP231 for others)
Manual Transmission Fluid:
Axle & Manual Transmission Lubricant, API GL-3, SAE 75W-90 (e.g., Mopar NV3550 Fluid, Red Line MT-90)
Automatic Transmission Fluid:
ATF+4 (MS-9602)
Transfer Case Fluid:
Mopar Multi-Purpose Gear Lubricant, API GL-5, SAE 75W-90 (or equivalent)
NHTSA Front Impact Driver:
4 Stars (2003 Model Year)
NHTSA Front Impact Passenger:
4 Stars (2003 Model Year)
Braking System:
Front Disc, Rear Drum (standard for most trims)
ABS:
Optional on some trims, standard on others (typically front wheels only for this era).
Airbags:
Driver and Passenger Front Airbags
Seat Belts:
Three-point front seat belts, lap belts in rear
Oil Change Interval:
Every 3,000-5,000 miles or 6 months, whichever comes first (refer to manual for exact recommendation based on driving conditions).
Transmission Fluid Change Manual:
Approx. every 30,000-60,000 miles, or as specified in the manual.
Transmission Fluid Change Automatic:
Every 30,000-45,000 miles (ATF+4 is often considered a longer-life fluid).
Coolant Flush:
Every 2 years or 30,000-50,000 miles.
Engine Oil Specification:
API Certified SAE 10W-30 (e.g., Mopar 5W-30 Synthetic if using a higher grade, but 10W-30 is standard).
Engine Oil Capacity:
Approx. 5 quarts (4.7 liters) with filter change for the 4.0L.
Coolant Type:
Ethylene Glycol Antifreeze/Coolant, Mopar HOAT (Hybrid Organic Acid Technology) or equivalent.
Common Issues Tj:
Leaks (oil, coolant, transmission), rear main seal leaks, differential seal leaks, exhaust manifold cracks (on older 4.0L), rust (especially on frame and body tub), clutch wear (manual transmission), alternator and power steering pump failures.
Front Brakes:
Ventilated Disc
Rear Brakes:
Solid Disc (on Rubicon), Drum Brakes (on other trims)
Wheel Lug Nuts:
95 lb-ft (129 Nm)
Service Focus:
U-joints are common service items, especially for off-road use. CV joints are found on front axles for 4WD operation.
Jeep Legacy:
Rooted in WWII Willys MB, known for go-anywhere capability.
Tj Generation Intro:
Introduced for the 1997 model year, replacing the YJ Wrangler. Featured a coil-spring suspension system replacing the YJ's leaf springs, significantly improving ride quality and on-road handling.
2003 Updates:
Minor trim level adjustments and feature packaging changes for 2003. The 4-door Wrangler Unlimited (LJ) was introduced for the 2004 model year, but the 2003 manual focuses on the 2-door TJ.
Manufacturing Plant:
Toledo, Ohio, USA