Complete 1986-1987 Buick Grand National and Turbo Buick Wire Harness

OEM-Style Replacement with Modern Improvements

Electrical problems can make even the nicest Grand National feel unreliable. Random no-starts, intermittent sensor readings, weak grounds, brittle wiring, melted connectors, and decades of previous repairs can turn troubleshooting into a never-ending battle.

This complete engine wiring harness gives your 1986–1987 GNX, Buick Grand National, Turbo T, T-Type, or Turbo Buick a fresh electrical foundation you can trust.

At Watts Performance, we have used this exact harness to help put hundreds of Grand Nationals back on the road. It is one of the most important upgrades we recommend when the original wiring is damaged, brittle, heavily modified, or simply too old to remain dependable.

Built Like the Factory Harness—Only Better

This harness is designed as a direct replacement for the original engine harness while correcting several weaknesses found in the factory design.

Every harness is manufactured using:

• Brand-new, 125°C-rated automotive TXL wiring
• Original-style Packard connectors
• Improved engine grounding
• Extended connections in areas where the factory wiring was too short
• Sealed automotive-grade relays
• Separate positive power feeds
• Improved wire routing
• Factory-style fit, finish, and appearance

The result is a clean, professional installation that fits the car properly and eliminates decades of questionable wiring repairs.

Tested Before It Reaches Your Car

Every harness is 100% electronically inspected before shipment.

Specialized testing equipment checks:

• Point-to-point continuity
• Resistance throughout the complete harness
• Proper connector and circuit placement
• Overall electrical integrity

That means you are not receiving a harness that was simply assembled and placed in a box. It has been tested as a complete unit to help ensure proper operation right out of the package.

Installation Support from Watts Performance

We created a complete harness removal video to help walk you through the process and give you confidence before turning the first wrench.

Watch the Complete Engine Harness Removal Video

When you purchase from Watts Performance, you are buying a product we have personally used, installed, tested, and trusted on real Turbo Buick builds.

Vehicle Compatibility

Designed for:

• 1987 Buick GNX
• 1986 + 1987  Buick Grand National
• 1986 = 1987  Buick Turbo T, T Type, and V6 Turbo Limited

Important Ordering Information

This harness is commonly kept in stock. However, depending on current production demand, please allow up to two weeks for manufacturing.

Because each harness is a specialized electrical component, all sales are final and this product is non-returnable. 

Stop Chasing Old Electrical Problems

Your original wiring harness is nearly 40 years old. Instead of continuing to repair brittle wires, corroded terminals, poor grounds, and previous-owner modifications, replace the entire foundation with a professionally manufactured harness proven on hundreds of Turbo Buicks.

Fresh wiring. Stronger grounds. Factory fitment. Confidence every time you turn the key.