Gregory Bender
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Wiring: Diagnose issues with turn signals not flashing

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The following applies to a great many Tonti models, though the colors and specific fuse position used will vary on the very early and very late models. Reference the appropriate wiring diagram accordingly.

The basic wiring path:

I'll start by explaining the path the electricity flows in order to make the turn signals function:

  1. Power goes from the fuse panel (F2) to the turn signal flasher via a Blue/Black wire (ignition switch must be turned on).
  2. Power goes from the turn signal flasher to the handlebar switch (through Molex connections) via an Orange wire.
  3. Power then goes from the handlebar switch to the left and right turn signals (through Molex connections) via a Pink wire (for the right turn signals) or a Green/black wire (for the left turn signals).

Before you dig in...

To diagnose issues, you can use a multimeter...or a lot of times I find that a simple 12-volt test light works just as well (i.e., light bulb with an alligator clip and a probe).

  • Pre-check 1: Make sure that the fuse is not blown.
  • Pre-check 2: If you are using LED light bulbs in your turn signals, make sure that you are using a LED-compatible turn signal flasher.
  • Pre-check 3: Check all light bulbs in the turn signals to make sure that they have not burned out (e.g., broken filament).

Warning:

Keep the kill switch in the off position when the ignition switch is turned on. This will keep the coils from receiving power and getting too hot.

Step-by-step diagnosis of the turn signal circuit

  1. Start at the fuse panel. Make sure that the blue/black wire has 12-volt positive any time that the ignition switch is turned on.
  2. Go to the turn signal flasher. Make sure that the blue/black wire still has 12-volt positive any time that the ignition switch is turned on.
  3. At this point, disconnect the wires from the turn signal flasher and join them together. That is, connect the blue/black directly to the orange wire. Doing so makes diagnosis a lot easier. Of course, the turn signals will turn on solidly and not flash.
    • If you don't have a male-to-male connector for joining the terminals, you can generally bridge the connection by inserting a small nail between the insulation and the terminal. Just make sure that the nail doesn't make contact with anything other than the two terminals (to avoid blowing the fuse).
  4. Where you joined the blue/black to the orange, make sure that the orange wire still has 12-volt positive any time that the ignition switch is turned on.
  5. Gain access to the Molex plugs where connections are made. Sometimes this will require removing the fuel tank, removing the headlight from the headlight bucket, etc.
  6. Identify where the orange wire enters the Molex plugs. Make sure that the orange wire still has 12-volt positive any time that the ignition switch is turned on.
  7. Go to the other side of the Molex plug and identify the wire that mates with the orange wire. Make sure that the orange wire still has 12-volt positive any time that the ignition switch is turned on.
  8. Turn on the right side turn signal using the handlebar switch.
    1. Identify the pink wires at the Molex plug. They should have 12-volt positive.
      • Check on both sides of the Molex plugs.
    2. Go to each right side turn signal (front and rear) and verify that the pink wires still have 12-volt positive.
      • Check on both sides of all connections.
  9. Turn on the left side turn signal using the handlebar switch.
    1. Identify the green/black wires at the Molex plug. They should have 12-volt positive.
      • Check on both sides of the Molex plugs.
    2. Go to each left side turn signal (front and rear) and verify that the green/black wires still have 12-volt positive.
      • Check on both sides of all connections.
  10. If power is getting all the way to each bulb, but the bulbs are still not illuminating, then there is a ground/earth problem with the turn signals. Perhaps a painted bracket is preventing the body of the turns signal from conducting electricity.

I know this seems like a lot of steps, but hopefully this breaks it down into a simple, step-by-step approach. At some point you will find the issue and be able to address it accordingly.