Request for help: diagramming a relay

[BailOut]

Originally Posted by Tamago

30: common to battery 12V
87: common to "stereo power wire"
85: common to "starter solenoid 12V"
86: common to GROUND.
87a: not used

so, only when the starter solenoid is engaged, the relay is in operation. because you're using 87 (NO contact) you won't be powering anything when the key is turned off. and because you've hooked 30 to "constant" your ACC circuit will be backfed power directly from the battery during the "start" cycle. since the ACC circuit does not power high-draw items such as the windows or AC or fan or defrosters, you should not have an issue with battery draw during the "start" cycle.

sound good?

also, this can all be done right at the radio (no need to run a feed from the battery itself)

Ahh - now we're getting somewhere. Thanks! That sounds like a solid idea.

Though it can all be done "at the radio" where would I tap into the "starter solenoid 12V" line? From the engine compartment, I presume?