How to Troubleshoot the Bosch eBike System on Tern Bikes
Heads up!
Do not open the Bosch motor or battery. Doing so means tampering with conditions approved by the manufacturer, which introduces safety-related risks. Any attempt to open the motor or battery will almost certainly void all warranty claims with the manufacturer. If you have concerns about your Bosch electrical system, always consult your authorized Tern dealer for proper diagnosis and repair.
If your Tern ebike won’t turn on, the cause is often simple, such as a depleted battery, a loose connection, or a display issue. This guide walks you through some tips you can do yourself, and explains when it’s time to contact your Tern dealer.
Contents
- Tip 1: Check the battery pack
- Tip 2: Check the display
- Tip 3: Check the display and controller wires
- Tip 4: Reset the system
- When should I contact a dealer?
Tip 1: Check the battery pack
If your bike won’t turn on, start by checking the bike’s battery, also referred to as the battery pack.
- Is the battery pack properly installed and locked in place? If not, re-insert the pack and make sure you hear a click. The click means that the pack is securely in place.
- Check the connectors for dust, moisture, corrosion, and other damage.
- Check the remaining battery charge level.
- Check the LED indicators on your battery to see if they are flashing. If they are, there might be an error. See the table below for the LED indicator combinations and what they mean.
LED indicators on your Bosch battery pack
Error indicators | What it means | Solution |
|---|---|---|
| LEDs 2 and 4 are flashing | A defect is detected in the battery pack. | Contact your Tern dealer for assistance. |
| LEDs 1, 3, and 5 are flashing | The battery pack is outside of the charging temperature range (0-40°C / 32-104°F). | Let the battery reach the correct temperature range before charging. |
| No LEDs appear when turning on the battery | The battery pack is at or below 5% charge. | Charge your battery. |
Tip 2: Check the display
If the display is not turning on, here are a few things to check:
- Make sure the display is properly installed on the mount.
- Check for dust, dirt, or moisture on the mount. Wipe clean if needed.
- If the display has its own battery, check whether it needs to be replaced.
- Look for signs of water damage on the display or mount.
If the battery pack is working, use its power button to turn the ebike system on or off instead of using the display. If the display does turn on but shows an error code, refer to your Bosch manual or look up the error code on the Bosch website.
What do the LEDs on my bike’s LED Remote mean?
If your Tern bike has an LED Remote, errors are indicated through the LED lights.
- The LED to the right of the Bosch logo indicates the current assist level.
- The five LEDs to the left of the logo indicate the battery pack’s charge level.
Error indicators | What it means | Solution |
|---|---|---|
| All lights on the LED Remote are flashing white after switching the bike on | The Lock function has been activated, but the connected phone or the display is too far away, or Bluetooth is not activated on the phone. | When the LED Remote is switched on again, move the phone or display to a distance of less than 1 meter from the LED Remote. |
| The assist level LED flashes orange four times and remains orange | Error detected. | Look up the error on the Flow app home screen or the Bosch website. Press the Select (♦) button to remove the error message. |
| All LEDs are flashing red | Critical error. | Contact your Tern dealer for assistance. |
Note: If your Tern bike is equipped with ABS, the small LED to the right of the lowest battery level indicator shows the ABS status. The LED is off when ABS is working normally, and on when a fault is detected.
Tip 3: Check the display and controller wires
Inspect the external cables and look for loose or damaged wires that may affect the system’s connection. Display or controller cables may come loose or misalign without you noticing, which can happen during transport.
Some cables may have an indicator showing their correct orientation. In this case, carefully reinsert them and ensure that the indicator on the cable lines up with the one in the receiving port.
Tip 4: Reset the system
- Turn off the e-bike system completely.
- Remove the battery pack and wait for a few minutes.
- Reinstall the battery pack. Make sure you hear a click that indicates that the battery is locked in place, then try turning the system on again.
When should I contact a dealer?
If you have tried everything as explained above and your bike still won’t turn on, it means that your bike requires professional service. Contact your authorized Tern dealer or Bosch ebike service center for assistance.