OMC – Key-on alarm not working, other alarms OK - SOLVED

Electrical and electronic topics for small boats
calvin9834
Posts: 3
Joined: Thu Jun 21, 2018 12:25 pm

OMC – Key-on alarm not working, other alarms OK - SOLVED

Postby calvin9834 » Thu Jun 21, 2018 12:28 pm

Have a 1993 Johnson 200 TXAT. The key-on warning horn sound does not work. Did some tests and the horn itself works. Disconnected the temperature warning sensor and connected to ground and got a continuous warning sound On the alarm. VRO low oil alarm is also OK. I have read some posts in which the alarm is on all the time, but for my problem, the only time the alarm does not work is when the key is first turned on initially. It is supposed to have a quick sound on the alarm when the key is turned on. Voltage test on the ignition switch also seem to indicate that the switch is okay.

How can an ignition switch be tested?

Maybe the problem lies elsewhere.

Is the warning horn a single function item, that is, if the horn makes a sound, then it works under all conditions?

What is it in the ignition switch that makes the warning horn sound once and then not again?

Is there a circuit in the warning horn that is activated once only when the key is turned on that could be broken?

Is there possibly another circuit inside the warning horn that is activated only with the key on?
Last edited by calvin9834 on Fri Jun 22, 2018 4:06 pm, edited 1 time in total.

Seahorse
Posts: 43
Joined: Fri Oct 09, 2015 2:03 pm

Re: OMC – Key-on alarm not working, other alarms OK

Postby Seahorse » Fri Jun 22, 2018 12:10 pm

Did the horn previously give a short beep when the key was first turned on?

Does your warning horn have a separate black ground wire hooked up, or only the tan and purple-violet wires and no black wire?

calvin9834
Posts: 3
Joined: Thu Jun 21, 2018 12:25 pm

Re: OMC – Key-on alarm not working, other alarms OK

Postby calvin9834 » Fri Jun 22, 2018 2:31 pm

Yes, horn always beeped to indicate it was working. Turn key on, short beep sounds when all is working ok.

It's a bit funny - the alarms all work, it's the function that tells me that it is working that just does not work.

I have two VIOLET +12-Volt wires going to the switch (warning horn), one BROWN (TAN) wire going to switch (warning horn) and one BLACK wire going to switch (warning horn).

I checked it again and I seem to be able to hear a slight sound coming from the horn when the key is first turned on. Has to be really quiet though. Sound when horn is on is really loud. Wondering if there is a circuit in the horn itself that only works when the key is first turned on. Bad ground in the black wire maybe.

I could just buy a new horn, but at $90, it's an expensive gamble and I hate to start throwing expensive parts at it. If they were cheap, I'd just try replacing the parts, but a $90 per potential solution, this can get expensive.

I'll try grounding the BLACK wire and see what that does. Just really difficult to get to without cutting the insulation.

calvin9834
Posts: 3
Joined: Thu Jun 21, 2018 12:25 pm

Re: OMC – Key-on alarm not working, other alarms OK

Postby calvin9834 » Fri Jun 22, 2018 3:30 pm

Problem solved: put some WD40 in the key switch to see what happens. If I hold the key in a certain way while turning to the ON position, the warning horn does its thing: gives a short warning sound as it is supposed to. The problem appears to be in the ignition switch itself.

I can either get a new ignition switch, or live with it since I know it works, Not sure if something loose in the ignition switch could cause another problem. Hope this helps someone some time. Hope it also avoids unnecessary parts purchases.

Great feeling to know I solved it without throwing a bunch of money at it. Basking in the glory now.

By the way, the ignition switch is available for as little as $17. The horn is $80-90, less if used.