RadWagon Wiring Harness Replacement Guide

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The wiring harness is a component made of wires that connects the electrical components on your ebike. On the RadWagon, the wiring harness can be found at the front of the bike and runs through the downtube to connect to the controller near the seat tube.

The wiring harness can be replaced in the unlikely event it is damaged or determined to be non-functional by Rad Power Bikes Product Support. The process involves unplugging the connectors, removing the harness from the downtube and replacing it with a new one, then plugging in the connectors.

Follow the steps below to replace the wiring harness on your RadWagon, if needed. This guide uses a RadWagon 3 (2019), but the steps will be similar for most RadWagon models.

Tools needed:

Flat side cutters
Flat head screwdriver
String (a few inches longer than the length of the downtube)
Electrical tape
A few zip ties
The replacement wiring harness from Rad Power Bikes

Remove the Old Wiring Harness

Get the bike ready for maintenance. Turn off the bike, remove the battery, and press and hold MODE on the LCD display remote to discharge remaining power.
Unplug the connectors at the front of the bike.
1. Snip zip ties securing the cables.
2. Unplug the display connector. Untwist the metal portion of the connector, then pull each side directly apart, without twisting, to unplug.
3. Unplug the remaining connectors. Pull each connector directly apart, without twisting, to unplug.
Locate the wiring harness connector below the battery mounting tray and unplug the connector.
1. Trace the cable from the cable opening just below the battery mounting tray to the large black connector.
2. Snip the zip tie to access the connector.
3. Unplug the wiring harness connector. Pull each side of the connector directly apart, without twisting, to unplug.
Use a flat head screwdriver to carefully unseat the rubber grommets at the top and bottom of the downtube (show in the image below).
At the bottom of the downtube, securely tie the string to the wiring harness connector end. Tape the string to keep it secure on the connector end. The string will be used to pass the new wiring harness through the downtube.
Insert the connector end into the cable opening of the downtube.
Remove the wiring harness while threading the string through the downtube. At the top of the downtube, carefully pull the wiring harness cable out fully, making sure the string stays threadded through the entire length of the inside of the downtube. The string will come out of both the bottom and top cable openings.
Pass the upper grommet off the old wiring harness and onto the string.
Remove the tape and untie the string from the connector end. Allow the string to remain inside the downtube and for both of its ends to hang outside of both cable openings. Recycle the old wiring harness according to local rules.

Install the New Wiring Harness

Locate the new wiring harness.
Tie and tape the string coming out of the upper cable opening to the single-connector side of the wiring harness.
Gently insert the connector through the grommet and into the upper cable opening of the downtube.
At the lower cable opening, gently pull on the string to help move the wiring harness through the downtube, until the connector moves out of the opening.

Do NOT use any tools (other than the string and tape) to assist in directing the connector end out of the lower cable opening. Tools like pliers, screwdrivers, etc. can easily damage the connector pins and housing, especially when inserted from the lower cable opening upwards into the downtube.
Plug in the wiring harness.
1. Remove the tape and untie the string from the connector end.
2. Pass the connector end through the grommet.
3. Plug in the wiring harness connector ends. Locate both connector ends and inspect them. Line up the internal notches and pins (and external arrows) and press directly together, without twisting, to connect.
4. Reinstall the grommet on the lower cable opening.
At the upper cable opening, gently pull the wiring harness cable to add cable slack, then reinstall the grommet.
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.
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.
Replace any snipped zip ties and trim them to be flush and smooth.
Ensure the handlebar and front wheel can turn fully right and left without pulling any cables taught. If needed, carefully pull more of the wiring harness cable out of the upper cable opening of the downtube to add slack.
Reinstall the battery and test the bike fully before riding.