Skip to main content

Need help? Click the chat button in the lower right corner of your screen to connect with a Customer Support agent live. Mon-Fri: 8 am-5 pm PST, Sat-Sun: 9 am-3 pm PST

Rad Power Bikes Production Site

RadMini Step-Thru and RadExpand Wiring Harness Replacement Guide

The RadMini Step-Thru wiring harness can be replaced in the unlikely event it is damaged or determined to be non-functional by Rad Power Bikes Product Support.

Watch the video below and follow the instructions to replace the wiring harness on your RadMini Step-Thru. This guide uses a RadMini Step-Thru 2 as an example, but the steps will be the same for other RadMini Step-Thru and RadExpand folding ebike models.

Tool needed:

  • Flat side cutters
  • A flat head screwdriver
  • String a few inches longer than the length of the downtube
  • Electrical tape
  • A few zip ties
  • A friend to help hold the bike in place
  • The replacement wiring harness from Rad Power Bikes
Remove the Old Wiring Harness
  1. Get the bike ready for maintenance. Turn off the bike, remove the battery, and press and hold the MODE or POWER button (depending on which remote you have) to discharge remaining power.
    Turn off RadMini.gif
  2. Locate the wiring harness connector at the front of the bike.
  3. Unplug the display connector from the wiring harness. Snip zip ties as needed to create cable slack. Untwist the metal portion, then pull each side of the connector directly apart, without twisting, to unplug.
    Unplug display.gif
  4. Unplug the rest of the connectors from the wiring harness. Locate each connector then pull each side directly apart without twisting to unplug.
    Unplug all connectors.gif
  5. At the top and bottom of the downtube, use the flat head screwdriver and gentle pinching movements to carefully unseat the rubber grommets. Be careful to not damage the grommets during removal.
    Remove grommets.gif
  6. Create cable slack in the downtube. At the upper cable opening of the downtube, gently feed the wiring harness cable into the frame. At the same time, gently pull the wiring harness connector out of the lower cable opening of the downtube.
    Create slack.gif
  7. Locate and unplug the wiring harness connector at the bottom of the downtube. Snip zip ties as needed and unplug the connector.
    Unplug connector.gif
  8. Attach the string to the wiring harness end coming out of the bottom of the downtube. Tie one end of the string to the wiring harness connector, then use electrical tape on the string, knot, and cable. This will keep them attached while they move through the downtube. 
    Secure string1.gif
  9. Insert the connector end into the lower cable opening.
    Insert connector2.gif
  10. Carefully pull the wiring harness cable out of the upper cable opening, ensuring the string comes out of both the lower and upper cable openings and remains inside the downtube.
    Remove wiring harness (3).gif
    If it’s difficult to pull the connector end through the upper cable opening when the bike is unfolded
    , partially fold the bike frame. Unlock the frame hinge and fold the bike partway. Have a friend hold the bike to keep it steady if needed. Gently pull the cable through the opening at the hinge and guide the cables through the opening on the other side of the hinge. Unfold the bike carefully, making sure to not pinch the string or cables in the hinge, and lock the hinge securely.
    Fold bike.gif
  11. Remove the string from the wiring harness and allow the string to hang outside of both cable openings. Recycle the wiring harness according to local rules.
    Continue to the next section to install the new wiring harness.
Install the New Wiring Harness
  1. Locate the new wiring harness and orient it so the side with the single connector points toward the back of the bike.
    Orient cable.gif
  2. Attach the string coming out of the upper cable opening of the frame to the single connector end of the new wiring harness, then use electrical tape to cover the string and knot on the cable. Make sure the string is secured and that the tape has smoothed down the knot to make it as easy as possible for the connector to slide through the downtube.
    String.gif
  3. Carefully pass the connector and string into the upper cable opening of the downtube.
    Insert.gif
  4. At the lower cable opening, gently pull on the string until the connector moves out of the opening. Make sure the wiring harness connector passes through the grommet.
    Access wiring harness.gif
    If it’s difficult to pull the connector end through the lower cable opening when the bike is unfolded, partially fold the bike frame. Unlock the frame hinge and fold the bike partway. Have a friend hold the bike to keep it steady if needed. Pull the cable through the hinge openings until it comes out of the lower cable opening, then unfold the bike carefully, making sure to not pinch the string or cables in the hinge, and lock the hinge securely.
    Fold frame.gif
  5. Plug in the connector to the controller. Align the internal notch and pins (and external arrows) and press directly together, without twisting, to connect.
    Connect (2).gif
  6. Double-check that the wiring harness connector is secure and pass the connector into the lower cable opening.
    Insert (2).gif
  7. Carefully reinstall the top and bottom grommets. Gently work the grommet around the opening until it’s fully seated.
    Grommets.gif
  8. Plug in the connectors at the front of the bike.
    1. Plug in the display connector. Locate the connector ends with the silver metal portion. Line up the internal notch and pins (and external markings) and press directly together, without twisting, to connect. Then twist the metal portion together fully.
    2. Plug in the headlight connector. Trace the cable coming from the bottom of the wiring harness junction and locate the matching connector end coming out of the headlight. Line up the internal notch and pins (and external arrows) and press directly together, without twisting, to connect.
      Connect all.gif
    3. Plug in the remaining connectors. Plug in all other connectors at the front of the bike. Locate the wiring harness connector ends and the matching connector ends. Trace the cable from the part to the connector end and ensure the connectors match. Line up the internal notch and pins (and external arrows) and press directly together, without twisting, to connect.

      Do not plug in a connector to the wiring harness if it does not match in color and shape. Doing so could cause irreparable damage to the connector, the part, or the wiring harness.

    4. Replace any snipped zip ties and trim them to be flush and smooth.
    5. Check that all cables are free from any moving parts. Rotate the handlebar to ensure it can move freely and that there is enough cable slack.
    6. Reinstall the battery, test the bike fully before riding, and ride Rad!
  • Was this article helpful?