Hi al.l I have the Grom BT3 in the mazda 6 2006 model. I transferred it from the audi 3 with a new cable maz02s. I have tried to update the firmware via the sd card. I get the IPhone pairing with the grom unit but no connection with the mazda headunit. I have tried a range of different sd card 8 gb 4 gb I have checked the terminals at each end of the cable. The Stereo just does not seem to see the grom unit. The grom unit is just over a year old, so I don't think there is any problem with that. Any suggestions would be very welcome.