Dorman 31003 Alternator Extension Harness

Brand Dorman 31003
Package Contents Alternator Lead Extender
Terminal Gender Male
Terminal Material Plastic
Terminal Type Blade
Wire Gauge Measurement 14
Wire Quantity 2
Wiring Harness Length 13
Fits Chevrolet, GMC, and Oldsmobile · 8 vehicles

OE direct replacement. Matches the fit and function of the original harness.

Quality materials. Engineered for reliable performance and durability.

Blade terminals. Two-wire alternator lead extender with male terminals.

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Dorman 31003 Alternator Extension Harness

Dorman 31003 is an alternator extension harness built to match the fit and function of the original harness on specified vehicles. It uses a 13-inch harness length, 14-gauge wire, and a 2-wire layout with male blade terminals for a direct electrical connection.

Key Features

  • Alternator lead extender for charging system repairs
  • 13-inch wiring harness length for application-specific routing
  • 14-gauge wire construction for electrical continuity
  • 2-wire design with male blade terminals
  • Plastic terminal material
  • Engineered for reliable performance and durability

Detailed Description

This alternator extension harness is designed for charging and starting system service where the original alternator lead needs replacement or extension. Dorman 31003 is listed for 1990 and 1993 Chevrolet P30, 1990 and 1993 GMC P3500, and 1987-1990 Oldsmobile Cutlass Ciera applications. It is a practical OE-style replacement for technicians and owners servicing these vehicles, including Chevrolet P30 and GMC P3500 charging system repairs.

This part cross-references OE-style alternator lead extender applications for the same vehicle fitment. The Dorman 31003 part number is also commonly used when searching for an alternator extension harness for Chevrolet P30, GMC P3500, and Oldsmobile Cutlass Ciera models.

Common Repair Uses

  • Damaged alternator lead wiring
  • Broken or corroded blade-terminal connections
  • Charging system voltage drop caused by worn harnesses
  • Harness routing issues after alternator service
  • Electrical connection problems at the alternator lead extender

Installation Notes and Tips

Verify connector style, wire count, and harness length before installation. Match the male blade terminals and 2-wire configuration to the original alternator lead on the vehicle. Confirm routing clears moving parts and heat sources, and inspect the charging circuit for corrosion or damaged terminals before final assembly. For fitment, this part is listed for 1990 and 1993 Chevrolet P30, 1990 and 1993 GMC P3500, and 1987-1990 Oldsmobile Cutlass Ciera.

Quality Assurance

Dorman designs this alternator extension harness to match original fit and function on specified applications. It is manufactured from quality materials for dependable electrical performance and long-term durability.

This part fits 8 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelLitersCylindersPositionNotes
1993ChevroletP304.3LV6N/A
1993GMCP35004.3LV6N/A
1990ChevroletP303.9LL4N/A
1990GMCP35003.9LL4N/A
1990OldsmobileCutlass CieraN/A
1989OldsmobileCutlass CieraN/A
1988OldsmobileCutlass CieraN/A
1987OldsmobileCutlass CieraN/A