When I got my SVT, it had a horrible Alpine radio in it. The dimmer worked flawlessly though. I swapped it for a Sony XB-120BT and the wiring for the dimmer was exactly the same, but it won't dim. Tried my old Alpine again and it dims. Would I need to solder in a relay for the dimmer switch for the Sony? I had an MEX-N5100BT in my taurus that had the exact same issue. Any ideas?