LED Functions in B1 Diagnostic Tool

Translated on 19-09-2026, 2:54.

hi everyone,

I've had the B1 kit for a while now, and I still don't know what the individual LEDs are for. In my search, I found this:

Quote:

LEDs 1-3 serve as optical indicators for the signals on the L-line (LED 1) and K-line (LED 2 illuminates when data is flowing towards the vehicle.
D3 in the data flow direction towards the PC)

Does this also apply to the B! kit?

Sure, here is the translation of the text from German to English:

"Hello"
holger

Translated on 19-09-2026, 2:55.

Hello Holger,

The circuit diagram shows that:
Red LED off = power supply; the other LEDs indicate Rx/Tx, K-line, or L-line (green).

Best regards, Rainer.

Translated on 19-09-2026, 2:56.

hello rainer,

Thank you for the information.
Why does the L-line only have one LED? Isn't it also used as a K-line depending on the configuration?
Is there any information available on the topic of K/L lines, either in this forum or on the internet?

Sure, here is the translation of the text from German to English:

"Hello"
holger

Translated on 19-09-2026, 2:57.

Hi,

because the green LED indicates whether the system is operating in Tx-L-Line or Tx-K-Line mode, while Rx is displayed for both modes.

Best regards, Rainer.