Ignition Coil & Iridium Spark Plugs & Wire for Chevrolet Trailblazer EXT (2003-2004) 5.3L

High-Output Ignition Coil, Wire & Iridium Spark Plug Kit for 2003-2004 Chevrolet Trailblazer

What it Does: Completely renews primary and secondary ignition delivery on the 5.3L V8 to restore lost engine combustion efficiency, smooth idle stability, and eliminate load-induced misfires.

The Stock Trailblazer Thermal Breakdown

Under heavy towing and extended thermal cycling in the confined GMT370 engine bay, factory round coils and carbon-core wires experience severe dielectric fatigue. Internal primary and secondary windings develop micro-fractures, while factory silicone boots harden and leak high-voltage energy to ground. Concurrently, factory wire resistance climbs, degrading secondary voltage delivery and causing spark blowout, erratic idle, and catalytic-damaging unburnt fuel wash.

The Engineering Solution

This comprehensive service package replaces degraded components with round UF262/D585-style coils potted in high-grade dielectric epoxy to eliminate internal arc bridging. Paired with 8mm stranded-copper core silicone wires featuring stainless-steel heat-shield terminals, this assembly withstands exhaust manifold radiant heat without resistance spike. Fine-wire iridium spark plugs drop voltage requirements while delivering a concentrated spark kernel for complete combustion under full throttle load.

Technical Specifications

Compatibility

• 2003-2004 Chevrolet Trailblazer EXT (5.3L V8 LM4 Vortec)
• Direct interchange with round coil OE references: UF262, D585, C1251, 10457730, 12563293, 12573190, 8104577300, 8125731900, GN10119, 5C1082, E254, E254P, 52-1647, IC413, 6737101, 19005218
• Wire cross references: 12192195, 9748GG, 748GG, 748UU, 12622553, 88862397, 12656210, XS10388, 12192192, 7873
• Spark plug cross references: 19299585, 41-962

The Chevrolet Heavy-Duty Caliber

Engineered to handle the continuous payload and towing demands of the extended GMT370 platform, this ignition system delivers uncompromising spark consistency through steep grades and sustained high-RPM operation.