So I have a fair amount of experience programming and was thinking hey why not try and write a new controller for my motorcycle (I know, a bold idea) and if not that, at least redo the old wiring. The bike is a 1982 Yamaha Seca 750 so its not like there are tons of electronics going on but I thought I would hop in and ask about what some things are and stand for in the wiring diagram.

enter image description here enter image description here enter image description here

Here also is the entire diagram. enter image description here

If anyone has any good resources to start learning about this please feel free to send them my way!

  • \$\begingroup\$ what is your specific question? \$\endgroup\$
    – jsotola
    Commented Mar 10, 2022 at 1:56
  • 1
    \$\begingroup\$ @jsotola "What would this be called" \$\endgroup\$
    – Passerby
    Commented Mar 10, 2022 at 2:21
  • \$\begingroup\$ I would call it "The digital monitor system of something out of Star Wars.";) like the HAL9000 or more recently hardware abstraction layer (HAL) monitor \$\endgroup\$ Commented Mar 10, 2022 at 3:07

3 Answers 3


Those are just tables that show the switch connections. Each column is a connection with the wire color at the top, each row is a switch position, the lines with circles show which wires are connected together when the switch is in that position.

For example on the one that says Main Switch in the ON position the Red, Brown and BLue wires are connected together, and the two White/Red wires are connected. In the OFF position nothing is connected, and in the Park position Red and BLue are connected.

The wires are shown connecting to the bottom or top of the column that matches their color.

  • 1
    \$\begingroup\$ Oh okay that makes tons of sense, thanks for such a concise and understandable answer. That is going to make reading this a lot easier! \$\endgroup\$ Commented Mar 10, 2022 at 2:27

You seem to be asking about the "main switch," "Turn Switch" and "Dimmer Switch." They are multi-function switches that have two or more positions or states that each open and close several connections. It does not appear that there is a "controller." There is a monitor that must show the status of various components and perhaps a tachometer and speedometer display. It is not exactly clear how the engine and vehicle speed is transmitted to the monitor.

  • \$\begingroup\$ The tachometer appears to sense the pulses on the ignition primary and the speedometer uses a reed switch, so one would assume there's a magnet somewhere that closes the relay at a rate relative to the speed. \$\endgroup\$
    – GodJihyo
    Commented Mar 10, 2022 at 2:19
  • \$\begingroup\$ Oh yea the speedometer is analogue so that will just be a later edition, rpm from what I remember is a similar analogue input. Awesome ty tho \$\endgroup\$ Commented Mar 10, 2022 at 2:26

These are called state-transition tables or just state tables. They are used in multiple industries for different reasons but all show the general status of an object in a given state. You will see this in wiring diagrams or service manuals of bikes and cars alike. JDMs use them more often than US Domestics in my anecdotal experience.

Given a state on the left, the status of the wire connections (columns) above or below will match the row.

While they try to stick to input on top and output on bottom, the complexity of wiring makes that uncommon.

Some switches are simple like the lo/hi dimmer switch. It's just a Single Pole Double Throw SPDT switch, and sometimes will have a simple symbol. On/off (SPST) switches too. But switches like the turn signal switch are too complex to show with a simple symbol. For that one you have multiple states, some are momentary and some are constant. N is the neutral position, L and R are the constant Left and Right, but N (L -> N) is the momentary action (you hold the turn signal on instead of clicking it on). With the constant on, the canceling unit is connected to ground so it will cancel the turn signal after a turn or timer (your bike is more fancy than mine).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.