my parents have a vehicle in which the radio/ deck will stay on after you turn off the car. it will turn off when you open the door to leave. i was thinking of trying to get my accord to do that. (deck turns off with car... but you all ready knew that) so i thought of connecting the 12v remote wire to one of the devises power that stays on till you open the door after the car is off like the power windows. my deck also takes a while to start so if i have the car on but not the engine then if i start the engine the deck wont have to restart.

anyone have a warning or better idea?

 

taken from the12volt.com:

If you wish to keep the radio (or any other device that is powered by an accessory circuit) on until a door is opened, you can do so by creating a latch when the accessory is turned on with the relay shown below on the left, then breaking ground to the latch when a door is opened as shown with the relay below on the right. While this will keep the radio on, the entire accessory circuit will see 12V+ until a door is opened with the key in the off position.





If you want to prevent 12V+ from feeding back into the accessory circuit or have more than one device on this circuit and do not want all of them to stay powered, you can isolate the device you want to stay powered by cutting the accessory wire going to it and adding two 1 amp diodes and an additional relay as shown below. The first diode near the top left of the diagram is to prevent 12V+ from going back into the accessory circuit. The second diode between terminals 87 and 86 prevents the radio from pulling current through the first diode. If the second diode is not in place, the first diode will become toast. The additional relay is needed to prevent the radio from turning off when the key is in the accessory position and a door is open.



Below is the same set up as above for positive door triggers.

 

i recommend getting a Haynes manual for your car, and referencing the wiring diagrams so you know where you can access the door triggers.

that's the only way i'd do it - relays and the door trigger.

 

i have a mild knowledge of electronics. i know what a diode and relays are but i have never seen that symbol for a relay before and i cant figure it out. but that aside i knew there would be a relay and my question (rephrased) was if i could splice the wire in between the relay and the control for the window with my decks remote wire. thus eliminating the need to add parts. there would probably be more current draw but the deck only needs the remote line to turn it on not power it...?

 

that symbol is what a standard automobile relay looks like, with the proper terminal numbers. it's actually not a symbol at all, more of a wiring diagram.

the remote wire does not turn the deck on and off. the remote wire is an output from the deck to turn amps on and off. to control the deck you need to interrupt the ignition wire.

the deck will always restart with the ignition, since the ignition voltage is cut off during starting. there is no useful way around that other than adding a cap and transistor to a relay, when that same relay provides ignition power to the head unit - like when doing this to power your head unit directly from the battery while using the factory ignition wire for control of the relay coil:



the idea you have in your head won't work. if you want to achieve the result of retained accessory power, follow the relay diagrams above. relays are cheap. the whole installation is very inexpensive, just requires tapping the correct wiring. you must add parts to achieve your desired result.

 

the diagram outlines using these types of relays.

you're used to the electrical symbol for relays,

like these:

 

ok i get it now. the remote is from the deck not to it. thanks for all the help

 

Great post with great information..I think you got him handled Hope