2003 Chevrolet Trailblazer EXT

2003 Chevrolet Trailblazer EXT

Overview

The 2003 Chevrolet Trailblazer EXT, a full-size SUV built on the GMT360 platform, offered a blend of utility and passenger space, particularly with its extended wheelbase. It was available with robust inline-six and V8 engine options, paired with a reliable automatic transmission. While generally considered a capable vehicle for its time, like many SUVs of this era, it has specific areas that have shown a propensity for issues as the vehicles age. Owners often report on the durability of the powertrain, but attention is frequently drawn to the electrical system and certain suspension components. Understanding these common points of failure can help prospective buyers and current owners manage maintenance and repair costs effectively.

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Engine

4.2L Atlas LL8 I6

Intake Manifold Gasket Leak

• Symptoms: Coolant loss, overheating, white smoke from exhaust.
• Solution: Replacement of the intake manifold gasket.
• Cost: $300 - $600

Crankshaft Position Sensor Failure

• Symptoms: Engine stalling, no-start condition, check engine light.
• Solution: Replacement of the crankshaft position sensor.
• Cost: $150 - $300

5.3L LM4/LM7 V8

Active Fuel Management (AFM) Issues

• Symptoms: Misfires, rough idle, oil consumption, potential lifter failure.
• Solution: Deactivation of AFM system or repair/replacement of affected components.
• Cost: $500 - $2000+

Intake Manifold Gasket Leak

• Symptoms: Coolant loss, overheating, vacuum leaks.
• Solution: Replacement of the intake manifold gasket.
• Cost: $300 - $600

Transmission

4L60-E Automatic

Torque Converter Clutch (TCC) Failure

• Symptoms: Shuddering at highway speeds, slipping, P0742 code.
• Solution: Replacement of the torque converter.
• Cost: $600 - $1200

3-4 Clutch Pack Wear

• Symptoms: Delayed or harsh shifting into 3rd and 4th gear, slipping.
• Solution: Transmission rebuild or replacement.
• Cost: $1500 - $3000+

Suspension

Standard Chassis

Front Wheel Bearing Failure

• Symptoms: Grinding noise, humming sound that increases with speed, play in wheel.
• Solution: Replacement of the front wheel bearing assembly.
• Cost: $300 - $600

Ball Joint Wear

• Symptoms: Clunking noises over bumps, uneven tire wear, steering instability.
• Solution: Replacement of worn ball joints.
• Cost: $400 - $800

Electrical

Body Control Module (BCM)

BCM Malfunction

• Symptoms: Intermittent power windows, door locks, interior lights, dashboard warning lights.
• Solution: Reprogramming or replacement of the BCM.
• Cost: $400 - $800

HVAC Blower Motor Resistor

Resistor Failure

• Symptoms: HVAC fan only works on highest setting.
• Solution: Replacement of the blower motor resistor.
• Cost: $100 - $250

Exterior

Body Panels

Rear Quarter Panel Rust

• Symptoms: Corrosion and rust formation, particularly around the wheel wells and lower sections.
• Solution: Rust repair and repainting.
• Cost: $500 - $1500+

Interior

HVAC System

Blend Door Actuator Failure

• Symptoms: Inability to control temperature (stuck on hot or cold), no air flow from vents.
• Solution: Replacement of the blend door actuator.
• Cost: $200 - $400

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Summary Verdict

The 2003 Chevrolet Trailblazer EXT is a capable SUV with generally strong powertrain options. However, as it ages, common issues tend to emerge, particularly in the electrical system with BCM and HVAC resistor failures, and in the suspension with worn ball joints and wheel bearings. Engine-specific issues like intake manifold leaks on the I6 and AFM problems on the V8 are also noteworthy. Transmission reliability is decent, but torque converter and clutch pack issues can arise. Rust on the rear quarter panels is a concern in rust-prone areas. Regular maintenance and proactive inspection of these common problem areas are recommended for owners.