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How-to guide

Rad LCD display bikes dead controller or display: replacement options

For the RadCity 3 and 4, RadRover 5, RadWagon 4 and RadMini 4: Rad's own display and controller first, an Area 13 harness, and which aftermarket kits are outside this guide.

Last edited Nov 9, 2026 by Pedalwise team Edit History Add a subpage

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Time
1 to 2 hours

Tools

This guide is for Rad bikes with the LCD display and separate button remote, such as the RadCity 3 and 4, RadRover 5, RadWagon 4 and RadMini 4, when the display or the controller has died. Rad's RadCity error 30 guide confirms the RadCity 3 and 4 use an LCD display; check your manual for the others. Rule out plugs and the harness first with the error 30 page for your bike: RadCity 3 and 4, RadRover 5, RadWagon 4 or RadMini 4.

Turn the bike off, remove the battery and drain leftover power before you unplug anything, as Rad's guides describe. Never open the controller, display, motor or battery, and never cut or splice wires. If you aren't sure which part failed, find a shop.

When this makes sense

Rad's own parts come first. Each of Rad's controller guides says to replace the controller only when Rad Product Support tells you to, using a controller from Rad. Rad's LCD display replacement guide says the same for the display. When we read the first page of Rad's spare parts store on Nov 9, 2026, it listed batteries, lights, tires and saddles but no controllers or displays, so ask Product Support for those.

Riders consider aftermarket parts when Rad can't supply the part, the wait is long, or the bike is out of warranty.

Options

Rad's own LCD display (easy, plug and play)

  • What it replaces: the LCD and its button remote.
  • What's involved: Rad's guide has you untwist the silver barrel connector, pull the ends straight apart, remove the display and remote clamps with a 3 mm hex key, fit the new parts, then line up the notches, pins and arrows and push straight together before twisting only the silver barrel. The barrel should sit snug against its gasket.

Rad's own controller (moderate, plug and play)

Rad publishes a separate guide per model, so follow yours:

  • RadCity 4 and RadCity Step-Thru 3: the controller bolts to the frame with four bolts and two brackets; on the Step-Thru the battery tray comes off first.
  • RadWagon 4: four bolts, tightened a half turn at a time in an X pattern, with the cables passing between the seatstays.
  • RadRover 5: the harness connector sits inside the downtube, so pull it out gently and don't let it unplug inside the frame.
  • RadMini: Rad's 2019 and 2020 RadMini guide doesn't mention the RadMini 4, so ask Rad for the right part and steps.

What must match is simple here: the controller Rad supplies for your model. Pull every plug straight apart, never twist, and line up notches and pins when you reconnect.

Area 13 E-Bikes Rad wiring harness (easy to moderate)

If the fault turns out to be the harness, Area 13 E-Bikes sells a Rad Wiring Harness listed at $40 and in stock (read Nov 9, 2026). Area 13 says it fits Rad bikes from about 2017 to 2022, not the RadRover 6 or RadCity 5, and that it is an aftermarket part not affiliated with Rad. Confirm the fit for your model with Area 13 before ordering.

Area 13 controller and display kit (outside this guide)

Area 13 E-Bikes also sells controller and display kits for Rad bikes, but they are sold as higher power upgrades, so they are outside this guide.

A universal controller and display (not covered)

We didn't find a seller's page showing a universal KT style controller and display that fits these bikes at stock power. For how controllers and displays are matched in general, see E-bike controller and E-bike display.

Setting it up

  • After the swap, check the display powers on, assist levels change, the throttle works and the brakes cut the motor. See Check brake cutoff and throttle.
  • Set units and your preferred assist level. The videos below walk through the LCD menus.
  • Keep the speed limit at your bike's class. Class 1 and 2 stop motor help at 20 mph and Class 3 at 28 mph with pedal assist (Bosch, three class system).
  • Never enter a wrong wheel size to change the speed reading. The display's wheel size should match the real tire on the bike.
  • Going past your e-bike class limits can make the bike illegal on public roads and bike paths in many places, voids the warranty, and adds wear on the battery, motor and brakes. A bike set up as Class 3 needs a Class 3 label.

Videos

LCD Display Features | Rad Tech from Rad Power Bikes: the LCD display's functions and buttons.
RAD POWER BIKES COMPUTER/LCD MANUAL, RadRover, RadWagon & RadMini from Maya and John: owners walk through the LCD's screens and settings.
Rad Power Bikes Electrical Issues (Solved) from Robinson Cycle: a shop tracks down an electrical fault on a Rad bike.

When to get a pro

Call a shop or Rad Product Support if the error returns after a careful connector check, if a plug is bent, burnt or wet inside, or if you can't tell whether the display, harness or controller failed. A tech can run the no power diagnosis.

Sources

Stuck after these checks? Find a shop near you.

Need a pro?

If these steps didn't fix it, find a shop near you in our partner network. For battery or wiring trouble, look for shops marked Battery and electrical.

Talk

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