S90 T8 HVCH(high voltage coolant heater) to CPM (combustion preheater) swap problem

[IMAY2023]

Most likely you are missing the LIN connection from CPM to CCM. 
4/7 COMBUSTION PREHEATER MODULE (CPM) Pigtail YE 0,75   (A3). This is the same LIN BUS as the front right heated seat.   
Here is the wiring diagram for S/V90 https://forums.spaycetech.com/attachment.php?aid=334 Seqrch for CPM.