My Daimler/Majestic has the DBC2459 with the six speaker common ground. And that, as others have said, is the problem.
The second pic is the PCB from the radio (PCB P/N 099-7825-01), with the lamp module switched power wires (GR/BR, BR/WT) and the speaker ground (GR/BLK) connected to a relay to complete the circuit to ground (?).
The lamp control modules are switched power with glass tube fuses (pic 1). I used one as the switched power source for the radio.
Having removed this pcb from the radio I understand why the 3A fuse blew. I have no idea why Jaguar chose to control the lamp control modules through the radio (P/N 099-7825-01) and I will use a different switched power source?
Everything works with that 3A fuse replaced by a 25A fuse (head unit 10A, amp 15A). The wiring to the center fuse block (in the console) looks to be robust enough to handle the load. However, that circuit was designed to use a 3A fuse and not a 25A fuse. I'm in no particular hurry to complete my install. My goal is an electrically competent install. My current plan is to try to duplicate the circuit on the pcb using typical 30A relays for ground and a new switched power source for the head unit and amp.
Any thoughts? Any direction from electrical engineers?