Mercury alarm noise

[r_marczak_83]

on a 98 nitro with 90hp Mercury. I have a constant alarm that will not go away. The alarm has a purple wire and a brown/blue wire. I found it back at engine going to a temperature sensor. I unplugged it there and it still made noise. I unplugged it at the alarm and it quits. Can I leave this off until winter when I have more time to look into this? Or is there another thing I should check?

 

[enginepower]

Is the oil level low? Could be faulty oil level switch.

 

[Texasmark]

Oil and temp are parallel grounds for the alarm which is powered by the ignition switch being somewhere other than OFF. The red with purple stripe or purple wire is that "power from the ignition switch" distribution.

On some engines you have a warning module which modulates the oil into a square wave...beep rest beep rest sort of thing to indicate oil vs temp which is a solid alarm when the sensor closes, applying ground at around 195F block internal temp.

Disconnect your wiring harness inside the engine proper where your remote control cable attaches. Try whatever you did and had an alarm. If you still have it you have a short in your remote wiring harness. If not your problem is in the engine and you either have blue/white stripe wire problems or tan or tan/Lt. blue stripe problems. The oil is the float in the oil tank and the OT is a sensor in the water jacket cover on the rear of the block.

 

[r_marczak_83]

Is the oil level low? Could be faulty oil level switch.

It was 3\4 full..........

Also it is a constant ring.

 

[Texasmark]

If you don't have a modulator module either temp or oil will be constant. My manual had about 4 wiring harnesses for the Mercs it covered....mid range 3-4 cyl 75-125, by number if cylinders...... aka lots of minor differences depending on the engine, like low ball, jet, early year in the series it covers or later years.

You can find the module as it has the light blue/white stripe wire(s) from th oil sensor and a brown or brown lt/blue stripe for temp plus as I remember black for ground and red, red purple or purple for 12v

 

[r_marczak_83]

I changed the buzzer and now its a Beep Beep Beep instead of a constant Beep. Why would this change?

 

[enginepower]

Different buzzer chemistry that didn't work fast enough to determine constant beep from pulsed beep? Just curious why you would change a buzzer for this condition.

 

[Texasmark]

Look around your engine for a plastic, epoxy filled module, about an inch or so square with the following wires attached to the connector: Black, ground, Red power, Tan with lt blue stripe or straight tan, or both for oil/temp signal in, lt blue with white stripe possibly for oil (if not used as a PTT wire for the up signal in your engine), Tan for signal output to buzzer. If you don't have one of those I don't have an answer as to why the signal changed. If you do, the system probably is functioning properly and it's telling you that you you are having an oil sensor problem and from writings on this site, the magnet falling off the float is the usual cause of faulty alarms....alarm when the tank is ? full. On engine's comment, I have no idea.