1988 Jeep Comanche Service Manual

The 1988 Jeep Comanche is a compact pickup truck featuring 2WD and 4WD configurations, available with 2.5L 4-cylinder or 4.0L 6-cylinder engines, manual and automatic transmissions, and payload capacities up to 2,205 pounds. This service manual covers maintenance procedures, specifications, troubleshooting, and repair instructions for all major systems including engine, transmission, brakes, suspension, electrical, and body components.

1. Vehicle Specifications 2. Maintenance Schedule 3. Engine Systems 4. Transmission & Drivetrain 5. Brake System 6. Suspension & Steering 7. Electrical System 8. Body & Interior 9. Troubleshooting Guide 10. Technical Service Bulletins

Vehicle Specifications

Key specifications for 1988 Jeep Comanche models.

Specification	Details
Engine Options	2.5L AMC 150 I4, 4.0L AMC 242 I6
Transmission	AX-5 5-speed manual, AX-15 5-speed manual, AW-4 4-speed automatic
Drivetrain	2WD, Command-Trac 4WD, Selec-Trac 4WD
Payload Capacity	1,100 to 2,205 lbs depending on configuration
Bed Length	6-foot or 7-foot options
Fuel Capacity	18.5 gallons
Wheelbase	113.0 inches (short bed), 119.0 inches (long bed)
Gross Vehicle Weight	4,700 to 5,300 lbs
Brake System	Front disc, rear drum with power assist
Suspension	Front: SLA with coil springs, Rear: Leaf springs

Maintenance Schedule

Recommended maintenance intervals for optimal performance.

Oil and filter change: Every 3,000 miles or 3 months
Air filter replacement: Every 15,000 miles
Spark plugs: Every 30,000 miles
Coolant flush: Every 30,000 miles or 24 months
Transmission fluid: Every 15,000 miles for severe service
Transfer case fluid: Every 30,000 miles for 4WD models
Brake fluid: Every 30,000 miles or 24 months
Timing belt: 60,000 miles (4-cylinder models)

WARNING! Always use jack stands when working under vehicle. Use proper safety equipment.

Engine Systems

Service procedures for 2.5L and 4.0L engines.

2.5L I4 Engine: 150 CID, TBI fuel injection, 117 hp @ 5000 rpm, 135 lb-ft @ 3500 rpm
4.0L I6 Engine: 242 CID, MPI fuel injection, 177 hp @ 4500 rpm, 224 lb-ft @ 2500 rpm
Cooling System: 13.5 quart capacity, 195°F thermostat
Fuel System: TBI or MPI injection, 14-16 psi fuel pressure
Ignition System: Electronic ignition, 0.035" spark plug gap
Oil Capacity: 4.0L I6: 6 quarts with filter, 2.5L I4: 5 quarts with filter

Transmission & Drivetrain

Service procedures for manual and automatic transmissions.

Manual Transmission: AX-5 (2.5L), AX-15 (4.0L) - 5-speed, gear oil capacity 3.5 pints

Automatic Transmission: AW-4 4-speed electronic, fluid capacity 8.5 quarts (dry)

Transfer Case: NP 231 Command-Trac, NP 242 Selec-Trac, fluid capacity 2.2 pints

Front Axle: Dana 30, gear oil capacity 2.5 pints

Rear Axle: Dana 35 or Dana 44, gear oil capacity 2.5-3.0 pints

Brake System

Hydraulic brake system service and repair.

Front brakes: Disc, single piston caliper, 10.9" rotor
Rear brakes: Drum, 9x2.5" shoes
Master cylinder: Tandem type with 1" bore
Brake fluid: DOT 3, system capacity approx. 1 pint
Parking brake: Mechanical, rear wheel actuation

Tip: Always bleed brakes starting from wheel farthest from master cylinder.

Suspension & Steering

Front and rear suspension components and steering system.

Front suspension: Short-long arm (SLA) with coil springs
Rear suspension: Leaf springs with staggered shocks
Steering gear: Recirculating ball, 17:1 ratio
Power steering: Integral type, fluid capacity 2.5 pints
Wheel alignment: Caster +6° to +7°, Camber +0.25° to +0.75°, Toe-in 1/16" to 1/8"
Shock absorbers: Twin-tube hydraulic, front and rear

WARNING! Always support vehicle properly when working on suspension components.

Electrical System

Wiring diagrams and electrical component service.

Battery: 12V, 58 amp-hour, negative ground
Alternator: 90 amp output, internal regulator
Starter: Direct drive, 1.4 kW
Fuse panel: Under dashboard, 15 fuses total
Lighting: Sealed beam headlights, 12V system
Instrument cluster: Analog gauges with warning lights

Body & Interior

Body repair procedures and interior component service.

Body dimensions: Overall length 177.4" (short bed), 183.5" (long bed)

Paint codes: Multiple factory colors available

Interior trim: Bench seat or bucket seat configurations

Glass: Laminated windshield, tempered side glass

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
Engine won't start	Fuel, spark, or compression issue	Check fuel pressure, spark plugs, compression test
Poor fuel economy	Dirty air filter, O2 sensor, timing	Replace air filter, check O2 sensor, verify timing
Transmission slipping	Low fluid, worn clutch/bands	Check fluid level, adjust bands, inspect clutch
Brake pulling	Stuck caliper, contaminated pads	Inspect calipers, replace pads, flush fluid
Electrical issues	Bad grounds, corroded connections	Clean battery terminals, check ground connections

Service: Refer to specific system chapters for detailed repair procedures.

Technical Service Bulletins

Common service issues and factory updates for 1988 Comanche.

TSB 88-001: Rough idle on 4.0L engines - ECM recalibration required
TSB 88-015: 4WD shift linkage adjustment procedure
TSB 88-022: Brake pedal pulsation - Rotor machining specifications
TSB 88-035: Transmission fluid leak - Pan gasket replacement
TSB 88-047: Electrical - Dash gauge inaccuracy - Ground circuit repair

Note: Always check for latest TSBs before beginning major repairs.