This USB contains the wiring diagram made by GM for dealer mechanics. You can follow the wiring in your truck from bumper-to-bumper. It will help you to understand connector configurations, and locate & identify circuits, relays, and grounds. Although the schematic is in black and white, the color of each wire is noted. You will not find this diagram in your shop manual.

With the step-by-step illustrated instructions and specifications on this USB, you will have the information you need to get your project on the road and keep it there. Great if you have a hard copy that you want to keep clean. Buy now to own the best wiring diagrams for your vehicle on USB. We have manuals on paper also -- see our other items.

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You can use the information on this USB to restore all 1977-1979 Light Duty Truck models including half ton, three-quarter ton, one ton, 1500, 2500, 3500, C, K, G, P, Fenderside, Wideside, pickup, Sierra, Street Coupe, crew cab, bonus cab, Suburban, Blazer, Jimmy, stakebed, crew cab, van, Rally Van, STX, Gaucho, Gypsy, Vandura, van chassis, hi-cube van, Value Van, forward control chassis, Caballero, El Camino, and stepvan. Includes 2 wheel drive, 4 wheel drive, and dually models. Covers both gasoline and diesel engines. Includes van-based well as forward control motorhomes chassis, classes A & C. This USB covers the part of the motorhome manufactured by GM and does not cover motorhome bodies.

1977 Chevrolet El Camino Classic Standard Cab Pickup 2-Door

1977-1978 Chevrolet El Camino Conquista Standard Cab Pickup 2-Door

1977-1978 Chevrolet G30 Chevy Van Extended Cargo Van 3-Door

1977-1979 Chevrolet C10 Cheyenne Cab & Chassis 2-Door

1977-1979 Chevrolet C10 Cheyenne Standard Cab Pickup 2-Door

1977-1979 Chevrolet C10 Custom Deluxe Cab & Chassis 2-Door

1977-1979 Chevrolet C10 Custom Deluxe Standard Cab Pickup 2-Door

1977-1979 Chevrolet C10 Scottsdale Cab & Chassis 2-Door

1977-1979 Chevrolet C10 Scottsdale Standard Cab Pickup 2-Door

1977-1979 Chevrolet C10 Silverado Cab & Chassis 2-Door

1977-1979 Chevrolet C10 Silverado Standard Cab Pickup 2-Door

1977-1979 Chevrolet C10 Suburban Custom Deluxe Sport Utility 4-Door

1977-1979 Chevrolet C10 Suburban Scottsdale Sport Utility 4-Door

1977-1979 Chevrolet C10 Suburban Silverado Sport Utility 4-Door

1977-1979 Chevrolet C20 Cheyenne Cab & Chassis 2-Door

1977-1979 Chevrolet C20 Cheyenne Cab & Chassis 4-Door

1977-1979 Chevrolet C20 Cheyenne Crew Cab Pickup 4-Door

1977-1979 Chevrolet C20 Cheyenne Extended Cab Pickup 2-Door

1977-1979 Chevrolet C20 Cheyenne Standard Cab Pickup 2-Door

1977-1979 Chevrolet C20 Custom Deluxe Cab & Chassis 2-Door

1977-1979 Chevrolet C20 Custom Deluxe Cab & Chassis 4-Door

1977-1979 Chevrolet C20 Custom Deluxe Crew Cab Pickup 4-Door

1977-1979 Chevrolet C20 Custom Deluxe Extended Cab Pickup 2-Door

1977-1979 Chevrolet C20 Custom Deluxe Standard Cab Pickup 2-Door

1977-1979 Chevrolet C20 Scottsdale Cab & Chassis 2-Door

1977-1979 Chevrolet C20 Scottsdale Cab & Chassis 4-Door

1977-1979 Chevrolet C20 Scottsdale Crew Cab Pickup 4-Door

1977-1979 Chevrolet C20 Scottsdale Extended Cab Pickup 2-Door

1977-1979 Chevrolet C20 Scottsdale Standard Cab Pickup 2-Door

1977-1979 Chevrolet C20 Silverado Cab & Chassis 2-Door

1977-1979 Chevrolet C20 Silverado Cab & Chassis 4-Door

1977-1979 Chevrolet C20 Silverado Crew Cab Pickup 4-Door

1977-1979 Chevrolet C20 Silverado Extended Cab Pickup 2-Door

1977-1979 Chevrolet C20 Silverado Standard Cab Pickup 2-Door

1977-1979 Chevrolet C20 Suburban Custom Deluxe Sport Utility 4-Door

1977-1979 Chevrolet C20 Suburban Scottsdale Sport Utility 4-Door

1977-1979 Chevrolet C20 Suburban Silverado Sport Utility 4-Door

1977-1979 Chevrolet C30 Cheyenne Cab & Chassis 2-Door

1977-1979 Chevrolet C30 Cheyenne Cab & Chassis 4-Door

1977-1979 Chevrolet C30 Cheyenne Crew Cab Pickup 4-Door

1977-1979 Chevrolet C30 Cheyenne Extended Cab Pickup 2-Door

1977-1979 Chevrolet C30 Cheyenne Standard Cab Pickup 2-Door

1977-1979 Chevrolet C30 Custom Deluxe Cab & Chassis 2-Door

1977-1979 Chevrolet C30 Custom Deluxe Cab & Chassis 4-Door

1977-1979 Chevrolet C30 Custom Deluxe Crew Cab Pickup 4-Door

1977-1979 Chevrolet C30 Custom Deluxe Extended Cab Pickup 2-Door

1977-1979 Chevrolet C30 Custom Deluxe Standard Cab Pickup 2-Door

1977-1979 Chevrolet C30 Scottsdale Cab & Chassis 2-Door

1977-1979 Chevrolet C30 Scottsdale Cab & Chassis 4-Door

1977-1979 Chevrolet C30 Scottsdale Crew Cab Pickup 4-Door

1977-1979 Chevrolet C30 Scottsdale Extended Cab Pickup 2-Door

1977-1979 Chevrolet C30 Scottsdale Standard Cab Pickup 2-Door

1977-1979 Chevrolet C30 Silverado Cab & Chassis 2-Door

1977-1979 Chevrolet C30 Silverado Cab & Chassis 4-Door

1977-1979 Chevrolet C30 Silverado Crew Cab Pickup 4-Door

1977-1979 Chevrolet C30 Silverado Extended Cab Pickup 2-Door

1977-1979 Chevrolet C30 Silverado Standard Cab Pickup 2-Door

1977-1979 Chevrolet El Camino SS Standard Cab Pickup 2-Door

1977-1979 Chevrolet El Camino Standard Cab Pickup 2-Door

1977-1979 Chevrolet G10 Beauville Extended Passenger Van 3-Door

1977-1979 Chevrolet G10 Chevy Van Extended Cargo Van 3-Door

1977-1979 Chevrolet G10 Chevy Van Standard Cargo Van 3-Door

1977-1979 Chevrolet G10 Sportvan Extended Passenger Van 3-Door

1977-1979 Chevrolet G10 Sportvan Standard Passenger Van 3-Door

1977-1979 Chevrolet G20 Beauville Extended Passenger Van 3-Door

1977-1979 Chevrolet G20 Chevy Van Extended Cargo Van 3-Door

1977-1979 Chevrolet G20 Chevy Van Standard Cargo Van 3-Door

1977-1979 Chevrolet G20 Sportvan Extended Passenger Van 3-Door

1977-1979 Chevrolet G20 Sportvan Standard Passenger Van 3-Door

1977-1979 Chevrolet G30 Beauville Standard Passenger Van 3-Door

1977-1979 Chevrolet G30 Chevy Van Cutaway Van 2-Door

1977-1979 Chevrolet G30 Chevy Van Standard Cargo Van 3-Door

1977-1979 Chevrolet G30 Hi-Cube Cutaway Van 2-Door

1977-1979 Chevrolet G30 Sportvan Standard Passenger Van 3-Door

1977-1979 Chevrolet K10 Cheyenne Cab & Chassis 2-Door

1977-1979 Chevrolet K10 Cheyenne Standard Cab Pickup 2-Door

1977-1979 Chevrolet K10 Custom Deluxe Cab & Chassis 2-Door

1977-1979 Chevrolet K10 Custom Deluxe Standard Cab Pickup 2-Door

1977-1979 Chevrolet K10 Scottsdale Cab & Chassis 2-Door

1977-1979 Chevrolet K10 Scottsdale Standard Cab Pickup 2-Door

1977-1979 Chevrolet K10 Silverado Cab & Chassis 2-Door

1977-1979 Chevrolet K10 Silverado Standard Cab Pickup 2-Door

1977-1979 Chevrolet K10 Suburban Custom Deluxe Sport Utility 4-Door

1977-1979 Chevrolet K10 Suburban Scottsdale Sport Utility 4-Door

1977-1979 Chevrolet K10 Suburban Silverado Sport Utility 4-Door

1977-1979 Chevrolet K20 Cheyenne Cab & Chassis 2-Door

1977-1979 Chevrolet K20 Cheyenne Standard Cab Pickup 2-Door

1977-1979 Chevrolet K20 Custom Deluxe Cab & Chassis 2-Door

1977-1979 Chevrolet K20 Custom Deluxe Standard Cab Pickup 2-Door

1977-1979 Chevrolet K20 Scottsdale Cab & Chassis 2-Door

1977-1979 Chevrolet K20 Scottsdale Standard Cab Pickup 2-Door

1977-1979 Chevrolet K20 Silverado Cab & Chassis 2-Door

1977-1979 Chevrolet K20 Silverado Standard Cab Pickup 2-Door

1977-1979 Chevrolet K20 Suburban Custom Deluxe Sport Utility 4-Door

1977-1979 Chevrolet K20 Suburban Scottsdale Sport Utility 4-Door

1977-1979 Chevrolet K20 Suburban Silverado Sport Utility 4-Door

1977-1979 Chevrolet K30 Cheyenne Cab & Chassis 2-Door

1977-1979 Chevrolet K30 Cheyenne Cab & Chassis 4-Door

1977-1979 Chevrolet K30 Cheyenne Crew Cab Pickup 4-Door

1977-1979 Chevrolet K30 Cheyenne Standard Cab Pickup 2-Door

1977-1979 Chevrolet K30 Custom Deluxe Cab & Chassis 2-Door

1977-1979 Chevrolet K30 Custom Deluxe Cab & Chassis 4-Door

1977-1979 Chevrolet K30 Custom Deluxe Crew Cab Pickup 4-Door

1977-1979 Chevrolet K30 Custom Deluxe Standard Cab Pickup 2-Door

1977-1979 Chevrolet K30 Scottsdale Cab & Chassis 2-Door

1977-1979 Chevrolet K30 Scottsdale Cab & Chassis 4-Door

1977-1979 Chevrolet K30 Scottsdale Crew Cab Pickup 4-Door

1977-1979 Chevrolet K30 Scottsdale Standard Cab Pickup 2-Door

1977-1979 Chevrolet K30 Silverado Cab & Chassis 2-Door

1977-1979 Chevrolet K30 Silverado Cab & Chassis 4-Door

1977-1979 Chevrolet K30 Silverado Crew Cab Pickup 4-Door

1977-1979 Chevrolet K30 Silverado Standard Cab Pickup 2-Door

1977-1979 Chevrolet K5 Blazer Cheyenne Sport Utility 2-Door

1977-1979 Chevrolet K5 Blazer Custom Deluxe Sport Utility 2-Door

1977-1979 Chevrolet P10 Step-Van Standard Cargo Van 2-Door

1977-1979 Chevrolet P10 Stripped Chassis 0-Door

1977-1979 Chevrolet P20 Step-Van Standard Cargo Van 2-Door

1977-1979 Chevrolet P20 Stripped Chassis 0-Door

1977-1979 Chevrolet P30 Step-Van Standard Cargo Van 2-Door

1977-1979 Chevrolet P30 Stripped Chassis 0-Door

1978-1979 Chevrolet C10 Big Ten Standard Cab Pickup 2-Door

1979 Chevrolet El Camino Royal Knight Standard Cab Pickup 2-Door

1977 GMC C15 Heavy Half Cab & Chassis 2-Door

1977 GMC C15 Indy Hauler Standard Cab Pickup 2-Door

1977-1978 GMC C15 Cab & Chassis 2-Door

1977-1978 GMC C15 Heavy Half Standard Cab Pickup 2-Door

1977-1978 GMC C15 High Sierra Cab & Chassis 2-Door

1977-1978 GMC C15 High Sierra Standard Cab Pickup 2-Door

1977-1978 GMC C15 Sierra Classic Cab & Chassis 2-Door

1977-1978 GMC C15 Sierra Classic Standard Cab Pickup 2-Door

1977-1978 GMC C15 Sierra Grande Cab & Chassis 2-Door

1977-1978 GMC C15 Sierra Grande Standard Cab Pickup 2-Door

1977-1978 GMC C15 Standard Cab Pickup 2-Door

1977-1978 GMC C15 Suburban High Sierra Sport Utility 4-Door

1977-1978 GMC C15 Suburban Sierra Classic Sport Utility 4-Door

1977-1978 GMC C15 Suburban Sierra Grande Sport Utility 4-Door

1977-1978 GMC C15 Suburban Sport Utility 4-Door

1977-1978 GMC C25 Cab & Chassis 2-Door

1977-1978 GMC C25 Cab & Chassis 4-Door

1977-1978 GMC C25 Crew Cab Pickup 4-Door

1977-1978 GMC C25 Extended Cab Pickup 2-Door

1977-1978 GMC C25 High Sierra Cab & Chassis 2-Door

1977-1978 GMC C25 High Sierra Cab & Chassis 4-Door

1977-1978 GMC C25 High Sierra Crew Cab Pickup 4-Door

1977-1978 GMC C25 High Sierra Extended Cab Pickup 2-Door

1977-1978 GMC C25 High Sierra Standard Cab Pickup 2-Door

1977-1978 GMC C25 Sierra Classic Cab & Chassis 2-Door

1977-1978 GMC C25 Sierra Classic Cab & Chassis 4-Door

1977-1978 GMC C25 Sierra Classic Crew Cab Pickup 4-Door

1977-1978 GMC C25 Sierra Classic Extended Cab Pickup 2-Door

1977-1978 GMC C25 Sierra Classic Standard Cab Pickup 2-Door

1977-1978 GMC C25 Sierra Grande Cab & Chassis 2-Door

1977-1978 GMC C25 Sierra Grande Cab & Chassis 4-Door

1977-1978 GMC C25 Sierra Grande Crew Cab Pickup 4-Door

1977-1978 GMC C25 Sierra Grande Extended Cab Pickup 2-Door

1977-1978 GMC C25 Sierra Grande Standard Cab Pickup 2-Door

1977-1978 GMC C25 Standard Cab Pickup 2-Door

1977-1978 GMC C25 Suburban High Sierra Sport Utility 4-Door

1977-1978 GMC C25 Suburban Sierra Classic Sport Utility 4-Door

1977-1978 GMC C25 Suburban Sierra Grande Sport Utility 4-Door

1977-1978 GMC C25 Suburban Sport Utility 4-Door

1977-1978 GMC C35 Cab & Chassis 2-Door

1977-1978 GMC C35 Cab & Chassis 4-Door

1977-1978 GMC C35 Crew Cab Pickup 4-Door

1977-1978 GMC C35 Extended Cab Pickup 2-Door

1977-1978 GMC C35 High Sierra Cab & Chassis 2-Door

1977-1978 GMC C35 High Sierra Cab & Chassis 4-Door

1977-1978 GMC C35 High Sierra Crew Cab Pickup 4-Door

1977-1978 GMC C35 High Sierra Standard Cab Pickup 2-Door

1977-1978 GMC C35 Sierra Classic Cab & Chassis 2-Door

1977-1978 GMC C35 Sierra Classic Cab & Chassis 4-Door

1977-1978 GMC C35 Sierra Classic Crew Cab Pickup 4-Door

1977-1978 GMC C35 Sierra Classic Standard Cab Pickup 2-Door

1977-1978 GMC C35 Sierra Grande Cab & Chassis 2-Door

1977-1978 GMC C35 Sierra Grande Cab & Chassis 4-Door

1977-1978 GMC C35 Sierra Grande Crew Cab Pickup 4-Door

1977-1978 GMC C35 Sierra Grande Standard Cab Pickup 2-Door

1977-1978 GMC C35 Standard Cab Pickup 2-Door

1977-1978 GMC G15 Rally Extended Passenger Van 3-Door

1977-1978 GMC G15 Rally Standard Passenger Van 3-Door

1977-1978 GMC G15 Rally STX Extended Passenger Van 3-Door

1977-1978 GMC G15 Vandura Extended Cargo Van 3-Door

1977-1978 GMC G15 Vandura Standard Cargo Van 3-Door

1977-1978 GMC G25 Rally Extended Passenger Van 3-Door

1977-1978 GMC G25 Rally Standard Passenger Van 3-Door

1977-1978 GMC G25 Rally STX Extended Passenger Van 3-Door

1977-1978 GMC G25 Vandura Extended Cargo Van 3-Door

1977-1978 GMC G25 Vandura Standard Cargo Van 3-Door

1977-1978 GMC G35 Magnavan Cutaway Van 2-Door

1977-1978 GMC G35 Rally Camper Special Cutaway Van 2-Door

1977-1978 GMC G35 Rally Standard Passenger Van 3-Door

1977-1978 GMC G35 Rally STX Standard Passenger Van 3-Door

1977-1978 GMC G35 Vandura Extended Cargo Van 3-Door

1977-1978 GMC G35 Vandura Special Cutaway Van 2-Door

1977-1978 GMC G35 Vandura Standard Cargo Van 3-Door

1977-1978 GMC K15 Cab & Chassis 2-Door

1977-1978 GMC K15 High Sierra Cab & Chassis 2-Door

1977-1978 GMC K15 High Sierra Standard Cab Pickup 2-Door

1977-1978 GMC K15 Sierra Classic Cab & Chassis 2-Door

1977-1978 GMC K15 Sierra Classic Standard Cab Pickup 2-Door

1977-1978 GMC K15 Sierra Grande Cab & Chassis 2-Door

1977-1978 GMC K15 Sierra Grande Standard Cab Pickup 2-Door

1977-1978 GMC K15 Standard Cab Pickup 2-Door

1977-1978 GMC K15 Suburban High Sierra Sport Utility 4-Door

1977-1978 GMC K15 Suburban Sierra Classic Sport Utility 4-Door

1977-1978 GMC K15 Suburban Sierra Grande Sport Utility 4-Door

1977-1978 GMC K15 Suburban Sport Utility 4-Door

1977-1978 GMC K25 Cab & Chassis 2-Door

1977-1978 GMC K25 Extended Cab Pickup 2-Door

1977-1978 GMC K25 High Sierra Cab & Chassis 2-Door

1977-1978 GMC K25 High Sierra Standard Cab Pickup 2-Door

1977-1978 GMC K25 Sierra Classic Cab & Chassis 2-Door

1977-1978 GMC K25 Sierra Classic Standard Cab Pickup 2-Door

1977-1978 GMC K25 Sierra Grande Cab & Chassis 2-Door

1977-1978 GMC K25 Sierra Grande Standard Cab Pickup 2-Door

1977-1978 GMC K25 Standard Cab Pickup 2-Door

1977-1978 GMC K25 Suburban High Sierra Sport Utility 4-Door

1977-1978 GMC K25 Suburban Sierra Classic Sport Utility 4-Door

1977-1978 GMC K25 Suburban Sierra Grande Sport Utility 4-Door

1977-1978 GMC K25 Suburban Sport Utility 4-Door

1977-1978 GMC K35 Cab & Chassis 2-Door

1977-1978 GMC K35 Cab & Chassis 4-Door

1977-1978 GMC K35 Crew Cab Pickup 4-Door

1977-1978 GMC K35 Extended Cab Pickup 2-Door

1977-1978 GMC K35 High Sierra Cab & Chassis 2-Door

1977-1978 GMC K35 High Sierra Cab & Chassis 4-Door

1977-1978 GMC K35 High Sierra Crew Cab Pickup 4-Door

1977-1978 GMC K35 High Sierra Standard Cab Pickup 2-Door

1977-1978 GMC K35 Sierra Classic Cab & Chassis 2-Door

1977-1978 GMC K35 Sierra Classic Cab & Chassis 4-Door

1977-1978 GMC K35 Sierra Classic Crew Cab Pickup 4-Door

1977-1978 GMC K35 Sierra Classic Standard Cab Pickup 2-Door

1977-1978 GMC K35 Sierra Grande Cab & Chassis 2-Door

1977-1978 GMC K35 Sierra Grande Cab & Chassis 4-Door

1977-1978 GMC K35 Sierra Grande Crew Cab Pickup 4-Door

1977-1978 GMC K35 Sierra Grande Standard Cab Pickup 2-Door

1977-1978 GMC K35 Standard Cab Pickup 2-Door

1977-1978 GMC P15 Stripped Chassis 0-Door

1977-1978 GMC P15 Value Van Standard Cargo Van 2-Door

1977-1978 GMC P25 Stripped Chassis 0-Door

1977-1978 GMC P25 Value Van Standard Cargo Van 2-Door

1977-1978 GMC P35 Stripped Chassis 0-Door

1977-1978 GMC P35 Value Van Standard Cargo Van 2-Door

1977-1979 GMC Jimmy High Sierra Sport Utility 2-Door

1977-1979 GMC Jimmy Sierra Classic Sport Utility 2-Door

1977-1979 GMC Jimmy Sierra Grande Sport Utility 2-Door

1977-1979 GMC Jimmy Sport Utility 2-Door

1977-1979 GMC Motorhome Chassis

1978 GMC C15 Street Coupe Standard Cab Pickup 2-Door

1978-1979 GMC Caballero Diablo Standard Cab Pickup 2-Door

1978-1979 GMC Caballero Laredo Standard Cab Pickup 2-Door

1978-1979 GMC Caballero Standard Cab Pickup 2-Door

1978-1979 GMC Jimmy Street Coupe Sport Utility 2-Door

1977 1978 1979 Chevrolet C10 Suburban C20 C30 El Camino G10 G20 G30 K10 K20 K30 K5 Blazer P10 P20 P30 GMC C15 C25 C35 Caballero G15 G25 G35 Jimmy K15 K25 K35 Motorhome Chassis P15 P25 P35