I’m finishing up the wiring on my hot rod project, and have installed a remote master battery disconnect solenoid switch (American Autowire #500834) in the positive battery cable. The solenoid can be actuated by either a negative ground pulse from a remote entry system, or by using a momentary pushbutton switch to ground that latches the solenoid either on or off.
Since I have some accessories that have memory circuits which need to be powered at all times, I’ve decided to install an American Autowire "Lifeline" retained memory jumper across the solenoid terminals. It's a resettable circuit breaker that will only flow 4 amps maximum, but will be enough to keep all of the memory circuits working.
I would like to have a visual confirmation of when the solenoid is latched or unlatched, but with the jumper installed, all of the circuits will always show power. My thought is to have a latching relay that could be triggered with the same pushbutton switch as the solenoid and synchronized with it so that it will power an indicator light when the solenoid is in the “on” latched position. If the light is off, the solenoid is unlatched, and I only have power for memory circuits; if the light is on, then the solenoid is latched and I’m good to start the vehicle. The thought here is that if I go to start the vehicle and the solenoid isn’t latched on, the breaker in the Lifeline will trip, which may wipe out all of the retained memory settings. Maybe not a big deal for the radio presets, but the fuel injection ECU settings may be lost.
I've read a lot of posts on latching relays, and have studied the relay diagrams of this site, but I don't want to install 3, 4, or 5 relays just to light a bulb. I understand that Omron makes plenty of latching relays but I'm unclear if these relays require two switches to make/break the connection or if only one momentary ground signal (from the same switch) will work.
If the latching relay is in sync with the solenoid relay, then I should have a way to monitor the solenoid's status.
If anyone can point me to a part # (and how to wire it up) or have a simpler way of doing what I want to do, I'd appreciate any help.
Thanks...