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6.5L GM Diesel OPS Bypass/Fuel Pump Harness Upgrade

6.5L GM Diesel OPS Bypass/Fuel Pump Harness Upgrade

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Fuel Pump Relay Wiring Harness for All 6.5L GM Diesels

Tired of OPS failures and the related headaches? Our fuel pump relay harness upgrade addresses the shortcomings of the oil pressure switch and the factory fuel pump wiring by reducing the load across the OPS from 4 amps to 150 milliamps in addition to carrying the actual fuel pump load through a high current relay. Furthermore, the system supplies power to the fuel pump through hefty 12 gauge wires as opposed to the factory 18 gauge setup. The result is vastly improved OPS reliability, extended fuel pump service life, and more consistent fuel pump performance. Additionally, some owners report significantly easier and quicker starts with less cranking.

Installation will take the average DIYer approximately 1 hour and requires only basic tools; all necessary hardware is included. This product is backed by a 1 year, unlimited mileage warranty.

This harness is available in three configurations that are model year specific - please select the correct part in the dropdown menu above for your vehicle application.


  • Reduces oil pressure switch electrical load from ~ 4 amps to ~ 150 milliamps (0.15 amps)
  • Adds wait-to-start priming for 1992 - 1994 and 1995 model year vehicles (1996+ applications already have this feature)
  • Provides more consistent voltage to the fuel lift pump
  • Prolongs oil pressure switch/sensor and fuel pump service life
  • Powers fuel pump through robust 12 AWG wires (vs factory 18 AWG)
  • High capacity 40 amp automotive relay
  • Constructed using OEM connectors for a perfect, problem-free fit and finish
  • 1 year, unlimited mileage warranty
  • Includes comprehensive, full color installation manual
  • Proudly made in the USA with primarily domestic materials


1992 - 2000 Chevrolet/GMC C2500, C3500 pickups (6.5L diesel)
1992 - 2000 Chevrolet/GMC K2500, K3500 pickups (6.5L diesel)
1994 - 1998 Chevrolet/GMC C1500 pickups (6.5L diesel)
1994 - 1999 Chevrolet/GMC K1500 pickups (6.5L diesel)
1992 - 2000 Chevrolet Suburban C2500 (6.5L diesel)
1994 - 1999 Chevrolet Suburban K1500, K2500 (6.5L diesel)
1994 - 1999 Chevrolet Suburban C1500 (6.5L diesel)
1992 - 2002 Chevrolet/GMC C3500HD chassis cab (6.5L diesel)
1995 - 1999 Chevrolet Tahoe (6.5L diesel)
1994 - 1999 GMC Yukon (6.5L diesel)
1994 - 1997 Chevrolet G20/G30 vans (6.5L diesel)
1992 - 1995 GMC G2500/G3500 vans (6.5L diesel)


Includes detailed instructions and all necessary hardware. Requires basic hand tools. All connectors are plug-and-play with the factory harness. To preview installation process, please see: 6.5L Diesel Fuel Pump Wiring Harness Upgrade Install


Manufacturer: REID TEKK
Part Number(s): RT-250301, RT-250301-A, RT-250301-B, RT-250301-C
Origin: USA
 Warranty: 1 yr, ul mileage
Shipping Weight: 2 lbs