This is your basic tractor wiring diagram. There are entirely too many different setups to even begin drawing or posting all of them on this website. The above diagram will give you an at a glance idea of how a tractor is wired up. The more bells and whistles on a tractor, the more wires and switches and relays. For example, the new garden tractors that have and electic PTO and a mow in reverse bypass switch. This setup requires the safety wiring system to run through the PTO switch and the introduction of a relay or two to allow the tractor to move backwards without killing the mowing deck or the engine.

The thing in the middle is the Ignition Swtich. Here are the designations for the letters:
B= Battery

When you turn and hold the key in the Start position to crank the engine over, the Battery and Start contacts touch to light up the Start terminal. When you release the key, they no longer touch and the Battery and Aux. contacts touch and the Magneto and Ground contacts break contact, to allow the engine to run. When you turn the engine off, the Ground and Magneto contacts touch, killing the engine and the Battery and Aux. contacts break contact to turn off the lights for anti-afterfire solenoid.

The Red wire from the stator is the DC circuit. This wire has a diode in it and it charges the battery. The black wire is the AC circuit and it does not have a diode. This circuit runs the light and electic PTO, if equipped.

Home | Questions?

updated 1-1-05

8 responses to “Basic Tractor wiring diagram”

  1. Rod says:

    G-Day Mate,

    Any chance of getting a copy of the above emailed to me? We have an old Murray that we can’t get the schematics for due to it’s old age and we are having a lot of trouble with. Your breakdown may help us.


  2. Dave says:

    What about the engine block mount? I am having an issue with a riding mower starter motor that is not grounded….im trying to find the bad ground but I have no idea where to look…

  3. Aaron says:

    Trying to finish the wiring on a 1974 Gilson model 53020 hydrostatic tractor and having some problems even with the manual. Care to have a look? I thought I had it wired right but when I tried it out I ran into some issues.

  4. Larry says:

    Where in this does the fuses go? trying to wire one from scratch and I’m sure there are supposed to be at least one fused area

  5. Robert E Lee says:

    I am building a go cart for my grandson and using the engine,B&S, from TroyBilt lawn tractor. Would you kindly forward a copy of your small engine wiring diagram. Thanks in advance.

  6. Michael says:

    You show the red and black for lights and charging of battery what do you do with them if there is no harness after that walk behind mower

  7. Norman Fox says:

    I have a 452CC McColloch engine. It has a 6 wire plug with 4 wires going to the engine. A blue wire goes to the carb. A black wire going to the coil/plug and 2 red wires going to the rectifier. I think the blue wire goes to the run terminal, the black wire to the m/mag. terminal. I don’t know what terminals the red/rectifier wires go to. The wiring diagrams I see only have 1 wire coming from the rectifier. Your help would be appreciated.

  8. russ bittinger says:

    i have a problem with a briggs motor i have juice now but as soon as i disconnect the red 14 goage wire i have to let it set for 20 min then it will have juice again is there a fusable link on a snapper 2752 269848 tractor if so where is it thanks russ

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