A Lionel e-unit wiring diagram

Lionel’s e-unit is the most common cause of trouble in vintage Lionel trains. Sometimes people bypass them or remove them entirely to avoid dealing with the problem. Or maybe someone attempted a repair in the past and you just bought the remnants. If someone did that and now you want to replace or rewire it, you need a Lionel e-unit wiring diagram.

You found one.

A Lionel e-unit diagram and explanation

Most Lionel e-units follow the conventions in the diagram below.

Lionel e-unit wiring diagram

The two yellow wires from the e-unit go to the motor brush holders. One wire usually reaches further than the other, so just attach them to whichever brushes they can reach. The e-unit usually has three more wires. One runs from the collector shoe or rollers to the e-unit coil. Another black wire runs from the coil to the headlight and/or the smoke unit. A third wire runs between the e-unit drum and the motor field. This wire may be black or green.

Further reading

I covered how a Lionel e-unit works in a separate post if you’re curious. It can seem like black magic, but essentially it uses a solenoid to change the motor’s polarity.

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2 thoughts on “A Lionel e-unit wiring diagram

  • December 3, 2018 at 11:50 am

    appreciate your post. My 97 yr old father was needing it to try and repair the stepping switch one more time or I suggested, take it out. My main challenge in keeping the family train going other than the fact its stuck in neutral this time, I think is cleaning the track and the pick up contacts on the engine. Any suggestion short of replacing all the boxes of track I have?
    Didn’t know if alcohol or acetone might be the best solvent/cleaner of the old rust, or might make it worse.


    • December 3, 2018 at 8:16 pm

      You might try spraying down the e-unit with some contact cleaner to try to fix it being stuck in neutral. If it’s just dirty, that will fix the problem. If there are worn out parts inside, you’ll need to get it rebuilt.

      My suggestion on the track would be to get some Evaporust or a similar rust remover. Auto parts stores and some hardware stores carry it. Soaking the track for a few hours in that will clean off all of the rust and should restore operation. Good luck!

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