90s System Monitor Wiring

Goatz

New Member
May 16, 2022
23
Gloucester, VA
Boat Info
1996 Sundancer 300
Engines
T-VD-5.7L Mercruiser - Blue Water Series - Thunder Bolt V - Closed Cooling
Hello All,
Hope it is not a miserable Memorial Day weekend, full or small craft wind warnings, rain, and thunder storm warnings where you are. I am looking for a wire diagram for the System Monitor circuit board. Specifically I am looking for where the audible alarm would connect. I removed it thinking it did not work. Well it worked fine when I tested it in my garage, but now don't remember where it connects. I have several open slots.
This is the monitoring system that is black, with an outline of the boat, has line 9ish leds and a switch at the top. Behind the dash there is a green circuit boat with a one sided terminal block down the left side.
I do know that one wire goes to the second from the bottom (Labeled Alarm). It is the other I am not sure of. They are labeled but I cannot get my head up there to see them.
Any help would be greatly appreciated and yes, next time I will take a pic first.
 
That alarm is connected to the circuit board that has the led's on it. Two wires, ground and power (Orange?). When the test switch at the top of the board is toggled then the alarm should sound. That board with the led's is semi-potted and very difficult to trouble shoot/repair. Usually when this happens it is toast. But to answer you question, remove the mounting screws and the board should come out. It's usually covered with red epoxy as a potting.
 
Thank You for your reply SKybolt. Unfortunately I don't think I explained correctly. What I am looking for is the board that visible board connects to. Here is a picture. This is why it took so long to reply as I needed to get a pic. Pic is not the greatest as I tried to clean up the board alittle. Was covered in mildew. So here is the board. The alarm (little buzzer) has two wires. The purple wire is positive and the other wire is white or tan with a blue stripe (neg). So what I am looking for is where do I wire it in. I assume one of them goes to that Alarm (second from the Bottom). But how about the other and would it be positive or neg. Access to this is minimal so tuff to even get a volt meter in there. Thank you.
 

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Thank You for your reply SKybolt. Unfortunately I don't think I explained correctly. What I am looking for is the board that visible board connects to. Here is a picture. This is why it took so long to reply as I needed to get a pic. Pic is not the greatest as I tried to clean up the board alittle. Was covered in mildew. So here is the board. The alarm (little buzzer) has two wires. The purple wire is positive and the other wire is white or tan with a blue stripe (neg). So what I am looking for is where do I wire it in. I assume one of them goes to that Alarm (second from the Bottom). But how about the other and would it be positive or neg. Access to this is minimal so tuff to even get a volt meter in there. Thank you.
Hi, did you resolve this. My monitor stops working sometimes, I suspect voltage sensitivity , but I may have to remove it to have a look. Whether wiring on my 400 is similar I don’t know but I can photo it if you think it will help you
 
No, this project has moved to the back burner as I have been working on other things. If you have a clear view of the circuit board, or you have to remove, it would really help to know which pins the audible alarm is connected to.
 
No, this project has moved to the back burner as I have been working on other things. If you have a clear view of the circuit board, or you have to remove, it would really help to know which pins the audible alarm is connected to.

It's in the pic you posted, 2nd in from the right labeled Alarm.
 
Where does the other wire go?
Does purple go to that spot or the tan with blue stripe? Or does it not matter?

Thank You
 
fake an alarm and check with a multi meter. The purple is 12v and tan is gnd. If I had to guess, the purple goes to 12v and the tan to the alarm lug.
 
Much appreciated. I will give it a try!
 

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