• Automotive test light with pointed end. Don’t leave home without it.

• Multimeter or continuity tester.

• Roll of 14 gauge wire to test with. You run a circuit along the side of the bike and if it works then you have a break somewhere. If you get sick of trying to decipher the harness, you just run a new wire with it. Not to mention, tape, connectors, etc.

There are several ways that the brake and taillight can be wired so it may be best to discuss this in a general manner. There are no real wiring color schemes on Changs you can count on, so I won’t. If you are really lucky black is ground.

Jeff has used relays for brake light and taillight on his wiring diagram. This is one of the best ways to go. Fuses or circuit breakers on the circuits with the relays would be even better.

Jeff’s diagram is here:

In the toolbox you can also find the article I did on installing an 1157 bulb holder in the taillight.

There are also a couple of articles that show how to open the headlight and install fuses.

The best thing to do, I think, is to separate the circuits in your mind so that you are only working one at a time.

Brake light

The brake light circuit should pick up power in the headlight area on the side that gets power whenever the switch is on in either run alone, or run with headlight on. It is best to test it in run alone mode as then it won’t confuse you with the headlight circuit which should be off.

In stock form my bike took power from the harness inside the shell and ran to a big fuse before it hit the ignition switch.

From the ignition switch the power runs to two European style white connectors that gang wires by fastening them in with screws. The one on the left facing the bike is for ignition and will be hot in either ignition or headlight mode. The one on the right on my bike is hot with the lights. These connectors could be wired either way, so don’t trust the position. Just put a test light on and try the ignition only position, only one should be hot.

• You need a wire from this hot while engine is on connector to the brake light switch. If it irritates you run another wire down there, there is usually plenty of room in the speedo grommet for another wire and it may save your sanity.

• From the brake light switch you need a wire to the taillight can. Usually there is one running along the underside of the fender and coming out a grommet, on my bike this ties to the frame. My brake light switch on my red bike is truly lame. It was pulling straight on the spring to start with and only came on for holidays in China. I drilled another hole to angle it down so that it operates with each application, apparently a novel concept. The other thing I don’t like it that not only is it cheesy plastic with plastic adjusting nuts, but it has no contacts to test on other than piercing the wires with a test light. It belongs on a refrigerator, not something your life rides on. First problem and it’s going to be replaced by a Harley or Honda switch.

• Check out the taillight article. Remember the Chinese bulb has weird contacts and you may wish to go to an American 1157. This will have one bright filament for the brake light and one dull one for the taillight. It also needs a ground. If you reverse them all that happens is the brake light is dull and taillight is very bright, so don’t solder or use connectors until you are sure.

Headlight:

From one white connector there should be a wire that is hot with the switch position for lights. This should have a wire fastened to it that goes to the handlebar light switch for high and low beam. This should have nothing to do with taillight and park light circuits unless you have a switch with a park position.

Ideally the taillight and sidecar light should come from the inside headlight wiring harness and hook to this white connector. If you are smart you will put a fuse between the white connector and the taillight circuit. This should have nothing whatsoever to do with the brake lights. The only thing that they share is to run inside the same wiring harness. This harness often has ends loose in the area of the rear fender. These loose wires can come from the taillight, brake light, and sidecar light. They can also run from the headlight area .It is nice if they are connected correctly but this does not always seem to happen.

If you already have a working taillight and sidecar light don’t worry any further about them, unless the filaments are reversed and you have a very bright taillight and no brake light.

Let’s look at what we want to happen.

We need one power wire to the stoplight switch. We need another wire from the switch to the taillight. We need the switch to actually operate when the pedal is depressed; we know this does not always happen in stock form.

We need a power wire from the headlight on connector to run back to the taillight area. This will likely come out in the area of the rear fender and will need to be connected to sidecar and taillight wires.