1988 GMT400-C2500 Manual PDF

The 1988 GMT400-C2500 is a full-size pickup truck from General Motors featuring a robust chassis, powerful engine options including the 5.0L V8 and 5.7L V8, rear-wheel drive configuration, and versatile payload capacity. This manual covers operation, maintenance, specifications, and troubleshooting for the C2500 model year 1988. Below are key sections for vehicle overview, specifications, operation, maintenance, and troubleshooting.

1. Vehicle Overview 2. Specifications 3. Operation Controls 4. Maintenance Schedule 5. Engine Systems 6. Electrical System 7. Braking System 8. Suspension & Steering 9. Troubleshooting 10. Warranty Information

Vehicle Overview

The GMT400 platform C2500 features a durable ladder frame, independent front suspension, and rear leaf spring setup. Key components include instrument cluster, steering column controls, HVAC system, and cargo bed.

Component	Description
Engine Options	5.0L V8 (305 CID), 5.7L V8 (350 CID)
Transmission	4-speed automatic (4L60) or 5-speed manual
Drivetrain	Rear-wheel drive with optional locking differential
Payload Capacity	Up to 2,500 lbs
Fuel System	Throttle body injection (TBI)
Braking System	Front disc, rear drum with power assist
Suspension	Independent front torsion bars, rear leaf springs
Steering	Power-assisted recirculating ball
Electrical	12-volt system with alternator
Fuel Capacity	25-34 gallons depending on tank configuration

Specifications

Model Year: 1988
Vehicle Type: Full-size pickup truck
Wheelbase: 131.5 inches (regular cab)
Overall Length: 194.5 inches
Overall Width: 76.8 inches
Overall Height: 70.5 inches
Curb Weight: 4,200-4,600 lbs
Gross Vehicle Weight: 6,200-6,600 lbs
Towing Capacity: Up to 7,000 lbs with proper equipment
Bed Length: 6.5 feet or 8 feet

Operation Controls

Dashboard controls include ignition switch, headlight switch, wiper controls, HVAC controls, and instrument cluster with speedometer, fuel gauge, temperature gauge, and warning lights.

Instrument Cluster: Speedometer (0-85 mph), Odometer, Trip Odometer, Fuel Gauge, Coolant Temperature, Oil Pressure, Voltmeter, Warning Lights (Brake, Check Engine, Battery, Oil).

Steering Column: Ignition switch, turn signal lever, wiper/washer control, tilt steering adjustment. Center Console: HVAC controls (temperature, fan speed, mode selector), radio, ashtray. Floor: Automatic shift lever or manual gearshift, parking brake.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Every 3,000 miles: Oil and filter change
Every 6,000 miles: Tire rotation, inspect brakes
Every 15,000 miles: Air filter replacement
Every 30,000 miles: Fuel filter replacement, spark plugs
Every 50,000 miles: Transmission fluid change
Every 100,000 miles: Coolant flush, timing belt (if equipped)
Seasonal: Check antifreeze protection, battery condition

WARNING! Always use recommended fluids and follow torque specifications.

Engine Systems

The 5.0L and 5.7L V8 engines feature throttle body injection, electronic ignition, and hydraulic lifters.

Starting Procedure: Insert key, turn to ON, wait for fuel pump to prime, turn to START
Cooling System: 16-18 psi radiator cap, 195°F thermostat
Fuel System: TBI injection, 12-14 psi fuel pressure
Ignition System: HEI distributor, electronic spark control
Lubrication: 5W-30 or 10W-30 oil, 5-quart capacity with filter

CAUTION! Never remove radiator cap when engine is hot.

Electrical System

12-volt negative ground system with alternator and maintenance-free battery.

Battery: Group 78, 650 CCA minimum
Alternator: 85-100 amp output
Fuses: Located in fuse block under dashboard
Bulb Types: Headlights (H6054), taillights (1157), turn signals (1156)
Charging System: Voltage should be 13.5-14.5 volts when running

Tip: Check battery terminals for corrosion regularly.

Braking System

Hydraulic power-assisted brakes with front disc and rear drum configuration.

Brake Fluid: DOT 3, check reservoir level monthly
Pad Replacement: Front pads should be replaced when worn to 1/8 inch
Drum Adjustment: Self-adjusting during reverse braking
Parking Brake: Adjust cable tension for proper holding
Bleeding: Required when air enters system or fluid changed

WARNING! Brake fluid absorbs moisture; replace every 2 years.

Suspension & Steering

Independent front torsion bar suspension with power steering.

Torsion Bars: Adjust for ride height; equal adjustment on both sides
Shock Absorbers: Replace in pairs when leaking or worn
Ball Joints: Check for play during tire rotation
Power Steering: Use Dexron II or III fluid; check for leaks
Alignment: Check if uneven tire wear or pulling occurs

CAUTION! Use proper jack points when lifting vehicle.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	Battery, fuel, ignition	Check battery voltage, fuel pump operation, spark at plugs
Rough idle	Vacuum leak, dirty injector	Inspect vacuum hoses, clean TBI unit, check EGR valve
Overheating	Coolant level, thermostat	Check coolant level, test thermostat, inspect radiator
Brake pulling	Stuck caliper, worn pads	Inspect calipers, replace uneven pads, check fluid
Electrical issues	Alternator, grounds	Test alternator output, clean battery terminals and grounds

Reset: Disconnect battery for 30 minutes to reset computer.

Service: Contact authorized GM dealership for technical support.

Warranty Information

Original warranty: 12 months/12,000 miles basic, 36 months/36,000 miles powertrain. Copyright © 1988 General Motors Corporation. All rights reserved. For technical support, contact your local Chevrolet dealership or GM customer service.