I had the dash out on my 187BR with 4.3 GL-D Volvo Penta engine to change the Faria RPM gauge last year and found that the alarm/buzzer with a crimped on post connection (to the red wire) was disconnected from any type of power source. This likely would be the alarm/buzzer for engine overheat for the riser sensors, thermostat overheat, or oil pressure sensor (all wires feeding those sensors is brown with a black stripe). The one wire (black negative) which is attached to the alarm/buzzer goes to a tan with a blue stripe wire in the main wiring harness. If I attach the positive (red) wire with crimped on post connection of the alarm/buzzer it goes off constantly when attached to a 12V power source.
Anyone have any thoughts why the alarm/buzzer would constantly go off when attached to a 12V power source with the key turned to just the on position, or even with the boat running? Any idea where I could get a wiring diagram for this year/model boat and engine?
The 10 pin wire harness does have a tan with blue stripe wire in it where mounted to the engine.
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Thank you. My sensor wires are definately brown with a blue strip. But, your advice worked. Unplugging oil pressure sensor wire (above the oil filter) made the alarm turn off. Looks like I need a new oil pressure sensor.
Tan with blue stripe comes from the senders on the engine. At least that's how mine is. I suspect that you have a bad sender, or you have a short to ground somewhere along that circuit.
Try disconnecting all of the senders and reconnect the positive to the buzzer. The goal is no sound at all. Then you would reconnect the sender wires one at a time until you find the culprit.
But if it you disconnect them all and it still buzzes, you may have a short. You can either trace the wire through the harness, or bypass it with a new wire.
Wire harness under dash showing the tan with blue stripe wire which goes to the negative wire of the alarm/buzzer....
10 pin harness showing there is a tan with blue stripe wire within it...
Alarm/Buzzer photo with the positive not connected to anything...