1988 GMC Sierra 1500 Owners Manual

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

1. Vehicle Overview 2. Instrument Panel 3. Starting & Operating 4. Specifications 5. Controls & Features 6. Maintenance Schedule 7. Fluid Capacities 8. Towing & Payload 9. Care & Cleaning 10. Warranty Information 11. Troubleshooting

Vehicle Overview

Key components: Engine compartment, instrument panel, seating, cargo bed, fuel system, electrical system.

Component	Description
Engine Options	4.3L V6, 5.0L V8, 5.7L V8
Transmission	4-speed manual, 3-speed automatic
Drivetrain	Rear-wheel drive, optional 4WD
Cab Styles	Regular cab, extended cab
Bed Length	6.5 ft or 8 ft
Fuel Capacity	25 gallons
GVWR	5,200 to 6,200 lbs
Brakes	Front disc, rear drum
Suspension	Independent front, leaf spring rear
Steering	Power steering standard

Instrument Panel

Main controls and indicators located on dashboard.

Speedometer: Shows vehicle speed in mph.
Tachometer: Engine RPM display.
Fuel Gauge: Indicates fuel level.
Temperature Gauge: Engine coolant temperature.
Oil Pressure Gauge: Engine oil pressure.
Warning Lights: Check engine, brake, battery, oil pressure.
Climate Controls: Heating and air conditioning system.
Audio System: AM/FM radio with cassette player.

WARNING! Always monitor warning lights while driving. Stop immediately if red warning lights illuminate.

Starting & Operating

Proper procedures for starting, driving, and shutting down vehicle.

Starting: Insert key, depress clutch (manual), turn to start position.
Shifting: Manual - use clutch pedal; Automatic - select gear with brake applied.
4WD Operation: Engage 4WD only at low speeds on slippery surfaces.
Parking: Apply parking brake, shift to Park (auto) or gear (manual).
Shutdown: Turn key to off position, remove key.

CAUTION! Never leave vehicle unattended with engine running. Always set parking brake.

Specifications

Engine: 4.3L V6 (120 hp), 5.0L V8 (150 hp), 5.7L V8 (165 hp)
Transmission: 4-speed manual, 3-speed automatic
Fuel System: Electronic fuel injection
Brakes: Power-assisted front disc/rear drum
Suspension: Independent front with coil springs, rear leaf springs
Steering: Power recirculating ball
Wheelbase: 117.5 inches (short), 131.5 inches (long)
Payload Capacity: 1,500 to 2,500 lbs
Towing Capacity: 5,000 to 8,000 lbs (properly equipped)

Controls & Features

Operating various vehicle systems and accessories.

Steering Column: Ignition, turn signals, headlight switch, wiper controls.

Climate: Temperature control, fan speed, vent selection, A/C button. Audio: Power, volume, tuner, cassette operation. Lights: Headlights, parking lights, interior dome light. Windows: Manual crank windows. Locks: Manual door locks.

Maintenance Schedule

Regular maintenance intervals for optimal performance.

Oil Change: Every 3,000 miles or 3 months
Filter Replacement: Air filter every 15,000 miles, fuel filter annually
Tire Rotation: Every 6,000 miles
Brake Inspection: Every 12,000 miles
Coolant Flush: Every 30,000 miles or 2 years
Transmission Fluid: Every 30,000 miles
Spark Plugs: Every 30,000 miles
Timing Belt: Every 60,000 miles (if equipped)

Tip: Keep maintenance records for warranty and resale value.

Fluid Capacities

Recommended fluid types and capacities.

Fluid Type	Capacity	Specification
Engine Oil	5 quarts	10W-30
Coolant	14 quarts	50/50 antifreeze
Automatic Transmission	12 quarts	Dexron II
Manual Transmission	3.5 pints	80W-90 gear oil
Transfer Case (4WD)	2.5 pints	80W-90 gear oil
Front Differential	3 pints	80W-90 gear oil
Rear Differential	4 pints	80W-90 gear oil
Brake Fluid	As needed	DOT 3
Power Steering	1.5 quarts	Power steering fluid

Towing & Payload

Proper procedures for towing and cargo loading.

Check ratings: Verify GVWR and towing capacity for your configuration.
Weight distribution: Load cargo evenly in bed.
Trailer hitch: Use Class III or IV hitch for heavy towing.
Trailer brakes: Required for trailers over 1,500 lbs.
Mirrors: Install extended mirrors for trailer visibility.
Practice: Get accustomed to trailer handling in safe area.

WARNING! Never exceed rated capacities. Overloading can cause loss of control and damage.

Care & Cleaning

Proper cleaning and preservation of vehicle surfaces.

Exterior: Wash with mild soap, dry with soft cloth. Wax every 3 months. Interior: Vacuum carpets, clean vinyl with mild detergent. Glass: Use glass cleaner and soft cloth. Chrome: Polish with chrome cleaner. Upholstery: Spot clean with upholstery cleaner.

CAUTION! Avoid abrasive cleaners. Do not use high-pressure washers on electrical components.

Warranty Information

GMC limited warranty coverage and terms.

Basic Warranty: 12 months/12,000 miles. Powertrain: 36 months/36,000 miles. Corrosion: 36 months/unlimited miles. Emissions: 24 months/24,000 miles (federal), 60 months/50,000 miles (California). For warranty claims, contact authorized GMC dealer with proof of purchase and maintenance records.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Battery, fuel, ignition	Check battery connections, fuel level, spark plugs
Rough idle	Spark plugs, fuel filter	Replace spark plugs, check fuel filter
Overheating	Coolant, thermostat	Check coolant level, replace thermostat
Brake vibration	Warped rotors	Resurface or replace brake rotors
Transmission slipping	Low fluid, worn bands	Check fluid level, service transmission
Electrical issues	Alternator, battery	Test charging system, check battery
Steering wander	Alignment, tires	Check wheel alignment, tire pressure
Fuel smell	Leaks, evaporative system	Inspect fuel lines, check gas cap

Service: Contact authorized GMC dealer for professional diagnosis and repair.

Customer Assistance: 1-800-GMC-8782