Does anyone know the function of the ZENEC IR input?

I would like to control my ZENEC Radio 2041D using the MFL interface.
"Those who follow my LIN project know that I'm not using the standard CAN-BUS commands; instead, I'm developing my own and using an Arduino to read the buttons."

The ZENEC radio has a single-wire "IR-Input" connector, to which, according to my research, the steering wheel adapter (or stalk adapter) would be connected.
I don't need any of that; I would like to use this connection to control the radio.
Does anyone know what kind of signals this input is expecting?

It's possible that we would need to send the same signals as a standard infrared remote control, perhaps with slight modifications, or maybe something completely different.

It would be great if someone had a suggestion, but otherwise, my only option seems to be to choose the path using an infrared transmitting diode and send the IR commands, as they are included in the remote control, to the radio.

Regards,
Marty.