1988 GMC Sierra SLE 1500 Owners Manual

The 1988 GMC Sierra SLE 1500 is a full-size pickup truck featuring V6 and V8 engine options, rear-wheel drive, automatic or manual transmission, power steering, air conditioning, AM/FM stereo, cloth bench seating, and various comfort and convenience features. Below are key sections for safety, features, maintenance, operation, specifications, and troubleshooting.

1. Features at a Glance 2. Vehicle Controls 3. Instrument Panel 4. Specifications 5. Maintenance Schedule 6. Driving Instructions 7. Towing and Payload 8. Safety Features 9. Care & Cleaning 10. Warranty Information 11. Troubleshooting

Features at a Glance

Key components: SLE trim package, V6 or V8 engine options, automatic transmission, power steering, air conditioning, AM/FM stereo, bench seating.

Feature	Description
Engine Options	4.3L V6 or 5.0L/5.7L V8 engines
Transmission	3-speed automatic or 4-speed manual
Drivetrain	Rear-wheel drive with optional 4WD
Power Steering	Standard power-assisted steering
Air Conditioning	Optional climate control system
Audio System	AM/FM stereo with cassette player
Seating	Cloth bench seat with SLE trim
Bed Length	6.5 ft or 8 ft cargo bed options
Fuel Capacity	20-gallon fuel tank
Payload Capacity	Up to 1,500 lbs depending on configuration

Vehicle Controls

Familiarize yourself with all vehicle controls before operating.

Ignition Switch: Located on steering column, positions include OFF, ACC, ON, START.
Headlight Switch: Pull-out knob on dashboard for headlights and parking lights.
Windshield Wipers: Multi-speed control on steering column.
Climate Controls: Rotary dials for temperature, fan speed, and vent selection.
Cruise Control: Optional feature with SET/ACCEL and COAST/RESUME buttons.

WARNING! Always ensure parking brake is engaged when parked on inclines.

Instrument Panel

Monitor all gauges and warning lights while driving.

Speedometer: Shows vehicle speed in mph.
Tachometer: Displays engine RPM (if equipped).
Fuel Gauge: Indicates fuel level in tank.
Temperature Gauge: Monitors engine coolant temperature.
Oil Pressure Gauge: Shows engine oil pressure.
Warning Lights: BRAKE, CHECK ENGINE, OIL, BATTERY, and seat belt indicators.

CAUTION! If any warning light illuminates while driving, stop vehicle safely and investigate cause.

Specifications

Engine: 4.3L V6 (standard) or 5.0L/5.7L V8 (optional)
Horsepower: 150-210 hp depending on engine
Torque: 230-300 lb-ft depending on engine
Transmission: 3-speed automatic or 4-speed manual
Fuel System: Electronic fuel injection
Brakes: Front disc, rear drum with power assist
Suspension: Independent front, leaf spring rear
Wheelbase: 117.5 inches (short bed) or 131.5 inches (long bed)
GVWR: 5,200 to 6,200 lbs depending on configuration
Fuel Type: Regular unleaded gasoline

Maintenance Schedule

Follow recommended maintenance intervals for optimal performance.

Every 3,000 miles: Oil and filter change, tire rotation

Every 6,000 miles: Inspect brakes, check fluid levels

Every 15,000 miles: Replace air filter, inspect belts and hoses

Every 30,000 miles: Replace fuel filter, inspect suspension

Every 50,000 miles: Replace spark plugs, check timing

Engine: Check oil level regularly. Cooling: Maintain proper coolant level. Brakes: Inspect pads and linings. Tires: Maintain proper inflation pressure.

Driving Instructions

Proper operation ensures safety and vehicle longevity.

Starting: Depress brake, turn key to START position.
Shifting: Come to complete stop before changing gears.
Braking: Apply steady pressure, avoid sudden stops.
Acceleration: Smooth acceleration improves fuel economy.
Parking: Engage parking brake on inclines.

Tip: Allow engine to warm up for 30 seconds before driving in cold weather.

Towing and Payload

Follow proper procedures for towing and cargo loading.

Check ratings: Verify GVWR and towing capacity.
Weight distribution: Load cargo evenly in bed.
Trailer hitch: Use proper Class III hitch for towing.
Brake controller: Required for trailers over 1,500 lbs.
Mirrors: Install extended mirrors for trailer visibility.
Practice: Get accustomed to trailer handling in safe area.
Lights: Ensure all trailer lights function properly.
Safety chains: Always cross chains under trailer tongue.

WARNING! Do not exceed maximum payload or towing capacity. Overloading can cause brake failure and loss of control.

Safety Features

Seat Belts: Lap and shoulder belts for all occupants. Brakes: Power-assisted front disc/rear drum. Lighting: Headlights, taillights, turn signals, hazard lights.

Care & Cleaning

Exterior: Wash with mild soap, wax regularly. Interior: Vacuum carpets, clean vinyl with mild cleaner. Glass: Use automotive glass cleaner.

CAUTION! Do not use abrasive cleaners on paint or glass. Avoid high-pressure sprays on electrical components.

Warranty Information

Basic Warranty: 12 months/12,000 miles. Powertrain: 36 months/36,000 miles. Rust Through: 36 months/unlimited miles. For warranty claims, contact authorized GMC dealer. Keep maintenance records for warranty validation.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Battery/ignition/fuel	Check battery connections; verify fuel in tank; inspect spark plugs.
Rough idle	Spark plugs/fuel system	Replace spark plugs; check fuel filter; clean injectors.
Brake vibration	Warped rotors	Have rotors resurfaced or replaced; check brake pads.
Overheating	Coolant/thermostat	Check coolant level; replace thermostat; inspect water pump.
Electrical issues	Battery/alternator	Test battery and alternator; check ground connections.

Service: Contact authorized GMC dealer for professional service.

Emergency: GMC Roadside Assistance: 1-800-462-8782