My final post on this thread as I seemed to have finally located and corrected the root cause.
TL,DR: the front 12v power/cigarette lighter outlet was fried, I suspect from an overloaded power inverter. The easiest way to see if this is the reason you‘re seeing the symptoms is to plug something in to the outlet and see if the radio behaves as normally expected (I used a USB outlet converter). Also, check to see if fuse #17 is blown - if it is it will cause these symptoms.
Longer explanation: The front dash 12v power outlet is connected/fed to the same voltage supply line as the radio and flasher relay; the exact connection point is upstream of their respective fuses and downstream of the ignition switch. 12vdc was being fed from the unswitched relay power through the relay to its switched power connection, ”up” through the relay’s switched power fuse #19 and back down through fuse #18 to the radio accessory line, keeping the radio on. it was especially confusing because it seemed like power was clearly bleeding through the relay when maybe it shouldn’t, but is apparently normal.
Before getting another relay that might get fried by some undetected short, I shared doing all kinds of voltage and resistance checks, including start looking at the power outlet, which is supplied power via fuse #17. This is when I plugged in my USB power plug and noticed the voltage being applied to the radio accessory power line dropped to only a couple volts, which isn’t enough to cause the radio to turn on. And in fact the radio started turning off as expected when the key is turned to off. I don’t know and could not find proper test procedures for the outlet itself, but I suspect there is supposed to be a small inline resistor that provides a current path, which is what cause the voltage to drop. However, I also discovered that fuse 17 was blown, isolating the power outlet from the circuit and preventing the voltage to drop on the accessory power line like it should.
The blown fuse in slot #17 for the outlet is a 20A, when it should only be 15A. I cant say why there was a 20A fuse in that slot, the fact that it was blown and other symptoms makes me think an inverter was plugged into the outlet, ran hot, and fried the outlet at the same time the fuse blew. A completely open power outlet whoul be electrically the same as a blown fuse and allow the full 12 volts from the relay be applied to the accessory power line.
Finally, I happened to have a panel mount 12v USB receptacle, so I just replaced the factory outlet with that and all is working great!
TL,DR: the front 12v power/cigarette lighter outlet was fried, I suspect from an overloaded power inverter. The easiest way to see if this is the reason you‘re seeing the symptoms is to plug something in to the outlet and see if the radio behaves as normally expected (I used a USB outlet converter). Also, check to see if fuse #17 is blown - if it is it will cause these symptoms.
Longer explanation: The front dash 12v power outlet is connected/fed to the same voltage supply line as the radio and flasher relay; the exact connection point is upstream of their respective fuses and downstream of the ignition switch. 12vdc was being fed from the unswitched relay power through the relay to its switched power connection, ”up” through the relay’s switched power fuse #19 and back down through fuse #18 to the radio accessory line, keeping the radio on. it was especially confusing because it seemed like power was clearly bleeding through the relay when maybe it shouldn’t, but is apparently normal.
Before getting another relay that might get fried by some undetected short, I shared doing all kinds of voltage and resistance checks, including start looking at the power outlet, which is supplied power via fuse #17. This is when I plugged in my USB power plug and noticed the voltage being applied to the radio accessory power line dropped to only a couple volts, which isn’t enough to cause the radio to turn on. And in fact the radio started turning off as expected when the key is turned to off. I don’t know and could not find proper test procedures for the outlet itself, but I suspect there is supposed to be a small inline resistor that provides a current path, which is what cause the voltage to drop. However, I also discovered that fuse 17 was blown, isolating the power outlet from the circuit and preventing the voltage to drop on the accessory power line like it should.
The blown fuse in slot #17 for the outlet is a 20A, when it should only be 15A. I cant say why there was a 20A fuse in that slot, the fact that it was blown and other symptoms makes me think an inverter was plugged into the outlet, ran hot, and fried the outlet at the same time the fuse blew. A completely open power outlet whoul be electrically the same as a blown fuse and allow the full 12 volts from the relay be applied to the accessory power line.
Finally, I happened to have a panel mount 12v USB receptacle, so I just replaced the factory outlet with that and all is working great!
