switched fuse panel
 

anyone know of a fuse port or a wire that turns on when ignition is switched off, and visa versa. for a blinking led to turn on when i turn off the truck.

Re: switched fuse panel
 

You can use a relay to do this , you need one with 5 pins .
terminal 85 to ground
terminal 86 to switched power
terminal 30 goes to an constant power
terminal 87 is not used
terminal 87a goes to the power side of the led
this is how it works , start the truck the coil of the relay is energized , closing the contact to terminal 87 ,thus shutting off power to the led ,when you shut the truck off the coil deenergizes,the contact opens shunting power through terminal 87a to the led

Re: switched fuse panel
 

fantastic. thanks for that. I'll check my electronic supply store

Re: switched fuse panel
 

And no, there is no existing accessible circuit that does that already.

Re: switched fuse panel
 

i did this in my 1994 sonoma without a relay, i just dont remember where i wired it into the stock harness to do this. would i be looking for a spdt or a spst relay. wouldnt some sort of back voltage suppressor be needed for sensitive electronics such as using a simple diode? as in a "1n4001"

Re: switched fuse panel
 

I don't think you're going to find an existing circuit that is hot only when the key is off without some serious digging through electrical schematics. He will require a SPDT relay, as a single throw won't have an 87a terminal. No diode needed either.

Re: switched fuse panel
 

well that relay didn't work. wired as shown, but it's not designed to do as you mention. it will give the opposite effect where when I turn off the ignition it will not give me power I need it to give me 12 volt when ignition is off and to cut the voltage when it's on. no matter how I wired the spdt 5 pin switch.

Re: switched fuse panel
 

You're wiring it incorrectly then. As mazdaman described will work as described.

Re: switched fuse panel
 

its exactly as he described. all circuits have been metered for power, including a constant power and a switched power supply from the fuse block. it will not turn on the led when the ignition is off. i benched tested the relay also, and it will not do as what was described. yes it turns power on and off, but i need it to supply power to the led when its off. there is a #30 pin, 85, 86 and two 87 pins

Re: switched fuse panel
 

Then you're not doing it as described. The relay needs to have an 87a pin. Pin 87 gets power from pin 30 when the relay is energized. Pin 87a gets power from pin 30 when the relay is de-energized. If you have two 87's, than that's really strange and it is only a single throw relay. You need a SPDT relay with an 87a pin.

Re: switched fuse panel
 

first off to clarify , pin 30 goes to a constant power (it doesnt shut off with the key ) pin 85 goes to ground , pin 86 goes to a switched power source ( turns off with the key ) , you say you have 2 87 pins , this will not work for what you want , you need a 87 pin and a 87a pin . the 87a pin is wired to the led , you do not use the 87 pin .
this might help http://www.the12volt.com/relays/relays.asp

Re: switched fuse panel
 

then it must be the wrong relay. a normally open one is what i must have i thought it strange to have two labeled as #87. no matter how i benched tested it. i will have to order a normally closed relay. thanks again for the confirmation and post.

Re: switched fuse panel
 

What they've described will work, using pin 87a (the one in the center, surrounded by all the other pins) will give the opposite effect of pin 87 (top of the relay) no matter what..... if pin 87 has power when the truck is on, pin 87a will have no power, etc.

If your led isn't working, you could have the polarity of the led reversed or if you didn't use a resistor for the relay it might have simply blown. A couple seconds of 12v on a led will fry it every time.

Any 12v automotive relay should do just what you need as long as it has 5 pins.

Re: switched fuse panel
 

yeah, thanks. i do have a resistor installed i think i have a normally open relay because there is no #87A just two marked #87 for the output. i just ordered a couple from my electronics supplier with a #87a

Re: switched fuse panel
 

I don't know what you're using a resistor for. Nothing on this circuit should have a resistor of any kind on it (presuming you are using a 12v LED).