Willys CJ-2A Harness Wiring Willys CJ-2A Harness Wiring. Keyed coil under dash Standard coil on engine. 2-post Junction Block 3-post Junction Block. Wire from headlight switch to dimmer switch should be 12 ga. (3- white tracers) Hi-beam wire from dimmer to junction block should be 12 ga. Willys CJ2A Wiring Diagram - De-mystified Willys CJ2A Wiring Diagram - De-mystified. The CJ2As wiring is about as simple as it gets, but the wiring diagrams in the Willys manuals are a compromise, and can be confusing. Aside from being a schematic, they are also a layout, with the parts being shown in the same relative locations they would be on the vehicle.