Did you get anything figured out (this was an an old post)? I'm trying to do the same retrofit on my x5 and I'm running into a number of problems.

My 01 X5 also has a LCM III with C18 firmware. I have the RLS and LCM IV (with C21) from a 2004 X5. NCSEXPERT won't code the LCM.C21 with the ZCS from my 2001 (i get an error: ERROR_ECU_REJECTED_WRITE). I'm guessing my ZCS (with or without the RLS option) is not compatible with the LCM IV.C21. NCS will recode the LCM IV with the original ZCS from the 2004 X5 without an error.

I own a 2002 530i that has RLS and auto headlamps. It has LCM.C19 and has the correction options in the NCS trace file. I'm guessing I could recode this LCM to work in the X5, but I'm not ready to risk messing up my 530i yet.

Is there any way to flash the firmware in any of the LCM modules?

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2001 x5 4.4 125k