This is the original wiring diagram printed 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. The schematic measures 8.5" x 11" when folded up, and opens up to 11" by 38". The diagram pictured is an example of this type when folded, but is not the actual diagram for your vehicle. Buy now for the best electrical repair info - the factory wiring diagram.
1978 Truck Wiring Diagrams Models 10 thru 35 P Truck
This item is original.
11.00 x 8.50 x 0.10 inches
This manual covers 1978 Chevy & GMC forward control truck chassis, including three-quarter ton, one ton, P 10, P 20, P 30, P 15, P 25, P 35, forward control chassis and stepvan. Covers both gasoline and diesel engines. Includes class A forward control motor home chassis. This book covers the part of the motorhome manufactured by GM and will not cover motorhome bodies. To verify that this is the correct diagram for your truck, you can check your VIN code. The 2nd digit should be a P for the forward control model, the 4th digit should be a 1, 2, or 3 to indicate the 10, 20, or 30 series, and the 6th digit should be a 8 for the 1978 model year.
1978 Chevrolet P10 Step-Van Standard Cargo Van 2-Door
1978 Chevrolet P10 Stripped Chassis 0-Door
1978 Chevrolet P20 Step-Van Standard Cargo Van 2-Door
1978 Chevrolet P20 Stripped Chassis 0-Door
1978 Chevrolet P30 Step-Van Standard Cargo Van 2-Door
1978 Chevrolet P30 Stripped Chassis 0-Door
1978 GMC Motorhome Chassis
1978 GMC P15 Stripped Chassis 0-Door
1978 GMC P15 Value Van Standard Cargo Van 2-Door
1978 GMC P25 Stripped Chassis 0-Door
1978 GMC P25 Value Van Standard Cargo Van 2-Door
1978 GMC P35 Stripped Chassis 0-Door
1978 GMC P35 Value Van Standard Cargo Van 2-Door
1978 Chevrolet P10 1978 Chevrolet P20 1978 Chevrolet P30 1978 GMC Motorhome Chassis 1978 GMC P15 1978 GMC P25 1978 GMC P35