Help. I'm trying to power my XM Roady 2 from the cigarette lighter. Here's what happens. The minute I plug it in the cigarette adapter sends no power. When I remove the XM plug I measure the cigarette adapter and I have power. I tried the phone charger and lighter and both do the same. I then connected a Radio Shack adapter and measured the power at the other end. Sure enough I had power. The minute I attach a load the power stops. The devices work fine in my other vehicle. What gives?
'94 Honda Accord

Thanks