I'm in the middle of installing an AM/FM/XM/BT/DVD/GPS radio into my 2001 Ford POS.

I was thinking of tricking out the accessory (or ignition) power input to turn on with the key then delay the turn off when the key is off until a door opens. The logic of that is simple though I do question how much current I need supply.

Is the accessory input a simple signal or is there some current drawn here? The unit specs are mute, and I've already spliced the cable preventing a direct measurement.

(Seriously though, I do love my truck.)

 

My 2002 Chrysler minivan does exactly what you describe. The radio will keep going for a minute after the key is removed, unless the door is opened during that minute, in which case it goes off immediately when the door is opened.

I'm not sure I understand your question. What do you mean by accessory input?

 

There are two "power" inputs to the unit. One is the constant 12 V battery power, the other the accessory power that is switched on and off with the key. I would believe the former suplies the main current to run the thing, while the latter is mostly a switching signal with a low current draw.

I am asking to size that "delayed off" switch as I would have to make one. Is it switching milliamperes or amps? I assume it's is low current but I don't built circuits on a bedrock of assumptions.

 

I can see it both ways, and nobody can guess from here, so measure it. Which line jumps into power mode when the switch is in "accessory" position?

 

I also admit ignorance but my guess is that it's the other way, that the "smart" power supply is controlled by the vehicle and full power is delivered to the radio. I can't explain why you'd need to run two power wires to the radio.

 

One wire is definitely the main source of power. It is back stopped with a local (on radio) 15 amp fuse.

The accessory input is switched power that acts as an enable line. A radio needs both if it has features like a clock that needs constant power to keep on keeping on.

Not that I have done many car radio installs but I have never seen them run off just one power wire, excepting the times I wired them just that way so it would keep playing until I turned it off with the knobs.

I just want to do it the modern fancy way now that I have a modern fancy radio.

I put some 12v relays on order, that should be a safe and sure way to control the aux power in.