[PDF] WIRING DIAGRAMS - 73-87ChevyTrucks. Classic Chevy WIRING HARNESS AND WIRES Every wire is a specific size with colored or striped insulation that is indicated on the wiring diagrams. Insulation colors help to trace circuits and to make proper connections. Abbreviations and symbols used for indicating wire insulation colors and patterns are as follows: need headlight wiring diagram for 86 w/ 4 bulbs | Classic Oct 10, 2007Home Forums > Chevy & GMC Trucks by Year > 1973-1987 > need headlight wiring diagram for 86 w/ 4 bulbs. Discussion in '1973-1987' started by truckertommy, Oct 7, 2007. I try to get the 86 front wireing wed so you have it to wiring for the motor but it with single headlights on it. So the head light part no good to you.