Electrical Harness for a Vanguard Conversion

Here is the complete wiring harness and electrical diagram for the Silver Cushman Eagle pictured on my home page. The harness provides all the normal functions plus front turn signals and rear turn signals with their own auxiliary taillights. A relay and two steering diodes are used to allow the oil pressure warning light to do double duty as a turn signal indicator. A second relay is used for a starting interlock for safety when starting the bike. It will not start unless the brake petal is depressed. Both of these relays are widely available inexpensive 30 amp miniature automotive relays. They are very small, about a 1-inch cube. The terminal numbers shown on the diagram are the numbers you will find stenciled on the bottom of the relay. A standard electric start Silver Eagle ignition switch is used and it can be mounted either on the dash plate or on the side of the shroud. The accessory lead from the ignition switch turns on the headlight and tail lights. No separate light switch is but one can be added if desired. The Vanguard 12 volt lighting output is capable of running the lights and still charging the battery even at an idle.

Note: Two terminal numbers on the starter relay below are incorrect. Please reverse terminals 86 and 30. Terminal 86 goes to ground, 30 goes to the starter solenoid.

All wires are number 18 except those few designated as number 16. There are two black wires and two brown wires in the turn signal breakout so that the harness can divide under the rear fender and provide separate wires for each turn signal. Only one wire of each color is shown in the diagram for clarity but be sure to include both of them. A number is shown by a wire if more than one wire of that color is used. For those of you who are schematic challenged, when a wire is shown joining another at an angle it just it means that it is still a separate wire and that it continues to follow the joined wire to its termination where the wires are tied together. All like color wires are also joined at each termination. For instance, there are five black wires that terminate at the engine and they all tie together and ground to the engine block. There are two wires marked "battery" at the engine that tie together and go to the battery. One is the main power lead and the other is the brake light interlock lead. There are also four brown accessory wires that terminate at the engine. This is a junction point for the four brown wires, one from the accessory switch at the dash plate and the three feeding the tail and turn signal lights. The 12 volt output lead from the Vanguard regulator is also connected to the brown wires. Join all five wires together and insulate the joint with heat shrink tubing. If other accessories are used they can be connected here also. Note that connecting the Vanguard 12 volt output lead to the brown wires means that the output lead is connected to the lights at all times. This is the correct way to do it. When the key switch is turned off the Vanguard electronic regulator senses that no battery is present and shuts down instantly. In the original configuration using Vanguard's key switch the 12 volt lead is grounded when the key is switched off. Fuses are not shown for clarity but always use a fuse between the battery and the load. At the brake light switch the two leads marked "S1" tie together and go to one side of the switch. The lengths between the breakouts are shown but I suggest that you obtain a piece of white #18 electrical wire and, starting under the dash plate, run it just as the harness will go, past the engine and all the way to the tail light. Now take a magic marker and mark the wire at the best location for each of the breakouts shown.

I ran my harness from the dash plate, down the side of the scooter post as usual, around to the top center of the floor pan where it passes through to the underside of the pan through a large grommet. From there is very neatly fastened on the left side under the floor pan retaining clips and goes up under the scooter. The brake light wires breakout should line up with the switch and tie wrap across to the switch. The engine breakout passes through a grommet in the upper rear lip of the floor pan and goes up to the engine. The tail and turn harnesses continue rearward along the left frame. The cable dress in this area is a little different between the Eagle and the Silver Eagle because of the sub chassis on the SE and this is one reason I suggested using the white wire to verify the exact cable lengths and breakouts. The oil lead drops out as it passes the oil pressure switch. From there it depends upon your individual preference, but I found it very easy to dress it up under the rear fender. Once out of sight under the fender the turn signal cable splits and branches to each turn signal and the tail and stop wires continue to the light at the rear of the fender.

I have included this simplified drawing showing the breakouts. The best way to assemble this cable is to get a sheet of plywood or a long 1 x 6 and put large nails where the break outs will be. Then just lay each wire from its start to its termination around the nails. When all wires are laid out temporarily tape it enough to keep it together. There are several ways to turn these loose wires into a cable. You can simply wind them with black electrical tape but it looks bad and will get very messy with age. You can use the commercial plastic wraps or flexible tubes designed for this purpose but they look very amateurish. I think the only way to go is to use black polyester loom. It is available in Ľ and ˝ inch sizes. The ˝ inch size will take all the wires in the main harness and the Ľ inch will work fine for the tail and stop wires. It can be pulled down tightly over the wire and really looks professional. The only problem with it is that it will fray like a nylon rope when it is cut. I put it over the wires and temporarily tape it down about Ľ inch back from the end. Then I use a very sharp pair of diagonals or small scissors to trim the fray. Then use just a drop of CA glue from the model shop to cement it down to the wire. Use caution because the CA can wick down the polyester and make your cable stiff. When you have it secured at one end it is very easy to pull it down tight at the other and tape and glue again. For the small cables to the turn signal switch and the dimmer switch and perhaps even the tail and turn cables it is best to secure the loom where it splits apart and trim to exact length when terminating them at the far end. A standard dimmer switch can be used for the turn signals if you can remember to turn it off. Good luck, Happy Cush Vangarding. If you would like to have a clear printout from the CAD program send a SASE to Jim Frederick, P.O. Box 9245, Winter Haven, FL 33883. Be sure to specify which drawing you need.

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