Adding an audible warning at engine start - need help on the wiring

[full_boat_redo]

have a 1980 Lakes craft with a 1409 3.0 OMC I/O stern drive. I am adding an audible warning at start which has two wires coming out of the unit - the purple is the positive and the tan with blue stripe is the negative (tested with a 9 volt to confirm). Question is where should I tap in and connect them so that after the engine starts the warning will stop. Not sure if I should connect the purple with the other ignition wires on the gauges and the tan/blue somewhere else that will stop the connection post start or connect the tan/blue to the black ground and connect the purple to something else that will stop post start.

Thanks in advance for the help

 

[sam am I]

I was thinking on this a tad...............Appears to me what you have an audible alarm that is meant to be wired(as most are)such that it sounds off when something in the engine goes awry, e.g., overheat, low oil, etc,..........Which then is wired to +12V(purple) and "alarm out"(typically tan-blue and is a *active low)

You however explain what you desire the audible alarm to do, a bit differently? You want an alarm to sound to warning that the engine is about to be started? and then shut off when the engine spins up? Kinda a backup beeper but not, a "starting beeper"?

If I'm correct here and unless there is some factory wiring for this type of gig(I've never heard of this), I suppose I do something like this with an oil pressure switch. +12V(purple) and "alarm in"(tan-blue) to the oil pressure switch. Not a oil pressure sensor/sender thou, a "oil pressure switch"

http://www.autozone.com/autozone/par...fier=2279_0_0_

This will work in that when the Ig. is in the "on" position (pre-start), the alarm will be sounding due to +12 on purple(Ig. on) and ground((alarm in, no oil pressure) to the oil pressure switch. When the Ig. switch is moved to the start position, the starter will turn spinning/starting the engine, creating oil pressure and allowing the switch to open(un-ground), thus shutting off the alarm(post-start) when the engine is running......

BUT WAIT!! There's more.......if it happens to sound off while you're running, it doubles as a warning system that there is a low oil pressure issue. BONUS!!

You might want to test it a few times to make sure the oil pressure bleeds off(re-setting alarm) at a decent rate between a more rapid stopping and starting use. Should bleed off fairly fast thou, like 10 sec's'ish I'm thinking sounds reasonable. Depends I suppose on age of engine/wear on bearings.



****** "acitve low" is defined as a signal that is nominally high(+12 this case) and transitions to a low(0V or ground) upon a certain/defined condition(motor fault this case)

 

[midcarolina]

There are several ways to go about this......... you could simply add a normally closed oil pressure switch and a relay, then when oil pressures opens switch it will remove coil voltage from relay and silence alarm.