1990 250EXTD horn on low w Switch on

[Aquanut2]

After landing my 23' Grady hard in rough seas off a wave the horn came on low (not as loud as in past with a true alarm like low oil).
When measuring to ground the Yellow horn + lead has 12v with ignition on and with engine running it goes up to 14.7 which is normal charge voltage. The Pink to ground has 12v measured with engine running (this isn't good). When measured from the yellow to red feed I get 2.7 volts which is enough to sound the horn at low volume.

Thinking their may be a short in the Pink wire harness somewhere or voltage is getting through the CDI (where this wire comes from). This motor is pre YDS and my winkey is not showing any errors just the warm up and normal run blinks.

Unless I'm chasing the wrong rabbit my next things to check is the Pink wire continuity from the dash to the motor with the wiring harness disconnected for stray voltages, the thermo sensors which also have pink wires to them from the CDI or a bad ignition switch.

Suggestions are welcome.
Thanks for any help

[Aquanut2]

Need help on this one

Not keen when posters bump their own posts but have a big offshore tuna trip in two weeks and would love to get this resolved
Thanks

[rodbolt17]

your chasing wabbits.

power for the horn comes FROM the keyswitch yellow wire.
current flows from the switch,THROUGH the horn and down the pink wire to the ECU.
the ECU via the ground paths through the temp switch's and oil switch selects which alarm and RPM reduction.
low battery voltage can also sound the alarm.

[99yam40]

Have read about corrosion at inline fuse causing voltage drop,
Just something to look at

[Aquanut2]

Pink Wire is ground but has positive volts...

Thanks Rodbolt17 yes thats how I understand it works and the ignition switch should be fine if I read 12 volts on the yellow side to ground.
But with the horn disconnected should I be reading any positive volts on the pink wire coming from the CDI to ground with ignition on?
Thats the rabbit I'm chasing.

You helped me a month ago ended up replacing the CDI with a new used unit and engine has been running fine for a while now.

[Aquanut2]

Have read about corrosion at inline fuse causing voltage drop,
Just something to look at

Thanks 99yam40 checked both inline fuses on the harness by the ignition switch they have a rubber shielding and look clean but found a lot of dirty spade connectors on the grady's wiring system for lights and electronics.
Next I'll look at the battery side of things and the pink wire to ECU and ECU to sensors.

[Aquanut2]

your chasing wabbits.

power for the horn comes FROM the keyswitch yellow wire.
current flows from the switch,THROUGH the horn and down the pink wire to the ECU.
the ECU via the ground paths through the temp switch's and oil switch selects which alarm and RPM reduction.
low battery voltage can also sound the alarm.

RodBolt17 - Should I be reading any voltage on the pink wire to ground that leads from the boat side of a disconnected buzzer to the ECU?

[rodbolt17]

no.
the pink wire,best I can remember ,should not have 12V with the horn dissconecred.
unplug the ECU and retest it.

[Aquanut2]

Bet it's in the harness checking it out 2day

Thanks RodB will report back so others can benefit from my wabbits.
My thoughts exactly on the pink so will test. Way I see it can only be one of three things short in harness, connectors or bad ECU. the temp sensors could be bad but they act like a switch to ground and tested ok last time I looked.

Is there any value to a dead ECU? Do you know of a company that remans them? If it points to the puter this time around will drop $800 on a new vs. used off eBay.

Mike

[Aquanut2]

Wabbit Found!

Looks like the problems solved found a very corroded connector on the engine oil tank sensor, pins so bad they have to be replaced hope Radio shack has something that will pop into the socket.