Underhood ignition "hot" wire

[QDRHRSE]

Where's the best place to get a positive wire that is hooked into the ignition? I usually just poke around under the dash, find a hot wire, turn the car on and off to see if it is constant or not, and then I tap into it. Sometimes that can take a while. Is there anything under the hood that I could use.....I don't know off hand.

 

[j.speed]

If you are looking to use a power source that is on when the key is in the key on engine off position, I usually use the hot wire on the alternator. Or you could pick up a power source off one of the wires that come off the solenoid.

 

[jrichker]

The ignition coil is hot when the switch is in the run position. Use the red/green wire to trigger a relay. Run a fused wire to the relay contacts and you can suck as much juice as your relay & wiring can carry. All this is possible without harming the ignition circuit.

 

[THC420]

use the red wire on the coolant sensor that plugs into the overflow bottle. that is what i use for anything that needs 12V key on power to turn on a relay.

 

[QDRHRSE]

Perfect. I didn't want to use the coil wire (so I knew about that) but the other two ideas never even occured to me. The coolant sensor is perfect!!!!!

Thanks Guys