It's not important, if the connector is male or female, you have to take care for the electrical parameters. You have to take care that the RX/TX wires are crossed exactly once.BTW: ELM327 (and compatibles) are able to access the K line protocols too (if that connector really is a K line).
So, as long as I understood I must cross RX to TX ans TX to RX wires within the cable between TTL/RS232 converter and my existing K-Line/RS232 interface . Am I correct? Is it called null-modem if I am not mistaken?