How to Turn On or Troubleshoot Tern eBike Headlights

Is the headlight on your Tern electric bike not turning on? Here are my top 3 things I check on a Tern bike if the headlight isn’t turning on. These tips would cover the Tern Vektron, Tern HSD, and Tern GSD.

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8 thoughts on “How to Turn On or Troubleshoot Tern eBike Headlights”

  1. Thanks for posting this video. The first two items were are definitely something that many new Tern owners will benefit from as the fact there are two switches to control the light feels a bit unusual.

    I’ve had some problems on our HSD with the last issue. The wires seem very firmly attached, but when they’re touched or wiggled, the light flickers and sometimes goes off. Wiggling the wires usually resolves the problem, but it’s really frustrating when we’re out at night and the light goes out after hitting a bump in the road.

    Given that the connection to the prongs seems solid is it possible there is some look connection inside the lamp? Do you have any pictures of videos of the lamp disassembled?

    (Sending our bike in to our dealer for this type of issue isn’t really feasible so any DIY tips would be greatly appreciated!)

    1. Hey Ed – I’ve heard of folks having issues if the handlepost / front wheel have been rotated the wrong direction and the cables are being pulled too tightly causing a separating in the wire connections. I would back track on your wiring to see if anything is loose under the cable tie bundle.

    2. Thanks for the video! My GSD lights didn’t come on this morning so I used my backup lights and found your video after work. Didn’t think to check that light icon was off at the controller because both front and rear lights were out. Now I know BOTH lights are affected when the light icon is off, I assumed that would only affect the front light. I also learned that it’s pretty easy to accidentally turn them off!

  2. I am genuinely so grateful for this video, I was riding my bike last night and the lights wouldn’t come on. I had no idea there was a way to turn it on and off from the controller thingamabob and I have had this bike almost 2 years! Looking forward to checking out some more of your videos.

  3. Keith Bierman

    Very helpful! The older manuals (e.g. Vektron D8) available online would benefit from adding this information.

    What are the the connectors to the left of the headlight wires for?

  4. Thanks for this! Couldn’t work out why the lights suddenly weren’t working on a brand new bike! 🙂

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