If it read through the RJ45 in the remote mount then It should,and i emphasize,should,write to it fine. if it reads the code plug that means it is communicating with the radio,which is what you want. I haven't been able to get and of my CDM 1550's to read or write in remote mount through the RJ45. I have to uninstall the radio, reinstall the head on the radio and it will read and write just fine. Its just a pain having to do so since so many of my fleet has remote mounted CDM's. I talked to Moto tech suport and they were able to get on to program in there shop fine throught the RJ45. I talked to another tech in my shop and he thinks the remote cable that connects the radio and control head dont have all the wires that the internal ribbonn cable has. He also said to program the CDM's in remote mount conditions to program them through an accessory cable connected to the back of the chassis. Anyhow, hope this info helps you.