The issue was that I lost my PIN for the display and couldn’t find a way to bypass it. According to the KT-LCD3 documentation, there’s a method to copy all display values from another display without entering the PIN. You just need to send a specific UART packet to achieve this.

All you need are a computer and a USB to UART dongle, like this one:

usb to uart dongle

https://github.com/Jnnshschl/KTLCD3Reset

Download the latest exe (or compile it yourself) from the releases page and wire the UART dongle to the display’s UART interface like this:

  • KTLCD3 Blue => None
  • KTLCD3 Red => Battery + Positive
  • KTLCD3 Black => Battery - Negative
  • USB Red => None
  • USB Black => Battery - Negative
  • USB Green => KTLCD3 Green
  • USB Yellow => KTLCD3 Yellow

usb to uart dongle

  1. Start the Tool (replace COM8 with the port of your USB-to-UART converter)
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KTLCD3Reset-x64.exe COM8
  1. Turn on the Display
  2. Within 5s hold both UP and DOWN buttons for 2s
  3. Profit

The display should look like this if everything worked, if not try it again:

usb to uart dongle

If the process didn’t work, try repeating it over and over again!

How does this work

The tool performs a single function: it sends a byte sequence repeatedly over UART (9600 baud, 8 data bits, no parity, 1 stop bit). I recorded this byte sequence while C11 was set to 12.

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{0xFF,0x1C,0x19,0x00,0xA0,0x00,0x00,0x01,0x0B,0x02,0x00,0x00,0x00,0x0A,0x05,0x00,0x00,0x00,0x14,0x04,0x05,0x02,0x11}

These values represent the following data:

  • 255 (Reset Instruction?)
  • Wheel Diameter (inches)
  • Max Speed (km/h)
  • PAS Level
  • P1
  • P2
  • P3
  • P4
  • P5
  • C1
  • C2
  • C3
  • C4
  • C5
  • C6
  • C7
  • C8
  • C9
  • C10
  • C11
  • C12
  • C13
  • C14
  • CRC Checksum